Information
The downloads below will allow you to restore the Windows 7 default registry entries and program associations of the selected file extension type.
Note
This can be helpful for example when a file extension type opens with the wrong program by default, has the wrong icon, or is missing or corrupted in the registry. Downloading the .reg file for the selected file extension in the tutorial below, will restore that file extension back to default for all of these items above.
Since there are so many default file extension types in Windows 7, it may take a bit to have a complete list of them below. If the file extension type you need to restore is not listed below yet, then please post a request for it. I'll be happy to add it to the list.
Warning
Default program associations for file extensions are a per user setting by default, so you will need to be logged on to the effected user account to be able to restore the default associations of the file extension for that specific user account.
If you are logged in as a standard user and this still does not help, then have the administrator also merge the needed .reg for the file extension below while logged into their administrator account.
These default file extensions should only be used in Windows 7.
Here's How:1. Click on the link for the file extension below that you would like to restore the default associations of, and to download it's .reg file.
2. Save the .reg file to your desktop.
3. Right click on the downloaded .reg file and click on Merge.
NOTE: If you wish to see what changes will be made by the REG file, then you can right click on the extracted REG file and click on Edit to see the default registry entries that will be added. REG files are just text files. The "Edit" function just opens them in Notepad. 
Tip
If you do not see a
Merge option when you right click on the REG file, then you will need to check in
Default Programs to set the
reg file extension to have it's
Current Default program set as
Registry Editor (C:\Windows\regedit.exe). Afterwards, try merging the REG file again.
4. If prompted, click on Run, Yes (UAC), Yes, and OK.
NOTE: If you are logged in a standard user account, then you will get a Cannot import type error. Just click on OK for it. This is normal since what cannot be imported can only be done so by an administrator account instead. It will still restore the default association of the file extension though.
5. When done, you can delete the downloaded .zip and .reg files on the desktop if you like.
6. Log off and log on, or restart the computer to apply.
Default Windows 7 File Extension Types:
Note
To download all available file extension fixes below in one ZIP folder, click on the Download button below and save the ZIP file to your desktop. Open the ZIP file, and extract (drag and drop) the REG file for the file extension you want to restore to your desktop. Now you could just pick up at step 3 above.
3GP - Audio and video container format developed by the 3rd Generation Partnership Project (3GPP); designed as a multimedia format for transmitting audio and video files between 3G cell phones and over the Internet; commonly used by mobile phones that support video capture. The default program is Windows Media Player.
3GPP - Audio and video container format developed by the 3rd Generation Partnership Project (3GPP); designed as a multimedia format for transmitting audio and video files between 3G cell phones and over the Internet; commonly used by mobile phones that support video capture. The default program is Windows Media Player.
ani - Windows animated cursor file.
aspx - A file with the ASPX file extension is an ASP.NET Source file.
asf - Advanced Streaming Format (ASF) is an open file format specification for streaming multimedia files containing text, graphics, sound, video, and animation. The default program is Windows Media Player.
asx - Advanced Stream Redirector (.asx) play list files, also known as Windows Media Metafiles, are text files that provide information about a file stream and its presentation. The default program is Windows Media Player.
AudioCD - Audio CD protocol associations.
avi - Audio Video Interleave files. The default program is Windows Media Player.
bas - BASIC source code file.
bak - Usually used to rename a file extension with to make it a backup copy. bak as no associations by default, so this will remove all associations for the bak file extension.
bat - Batch files.
bin - Binary file. By default in Windows 7, .bin files are not associated to be opened by a default program.
bmp - Bitmap image files. The default program is Windows Photo Viewer.
Briefcase - New Briefcase file.
cab - Cabinet files.
chm - Microsoft compiled HTML help files.
cmd - Windows command script files.
com - MS-DOS application files.
Contact - Contact file. Default program is Windows Contacts.
cpp - Program source code written in the C++ programming language; may be a standalone program or one of many files referenced within a programming project; can be viewed with a text editor, but most software development programs will display the text with helpful syntax highlighting
css - Cascading Style Sheet Document file. The default program is Notepad.
cur - Windows File Cursor animation files used for the Microsoft Windows mouse pointer image.
dat - Generic data file created by a specific application; typically accessed only by the application that created the file; may contain data in text or binary format; text-based DAT files can be viewed in a text editor.
db - Data base file.
dic - The .DIC file extension is a Dictionary file (text file) which can be used as an alternate dictionary on top of the Microsoft Windows Dictionary and may contain an optional set of personalized words which the user has opted to add for spell- checking purposes.
Directory - Directory protocol associations
dll - A Dynamic Link Library (dll) file is a support file used by one or more programs.
drive - Drive protocol associations.
dvr-ms - Microsoft Recorded TV Show file. The default program is Windows Media Center.
exe - Executable application files.
folder - Folder protocol associations.
gif - GIF (Graphics Interchange Format) image files. The default program is Internet Explorer.
gz - Usually associated with Gzip. By default, there is no associated program for this in Windows 7.
h - C or C++ program language header file normally with .C or .CPP file. In computer programming, particularly in the C and C++ programming languages, a header file or include file is a file, usually in the form of source code, that is automatically included in another source file by the compiler. Typically, header files are included via compiler directives at the beginning (or head) of the other source file.
hlp - Help file
hta - HTML (Hypertext Mark-up Language) application. The default program is Microsoft (R) HTML Application host (mshta.exe)
htm - HTML (Hypertext Mark-up Language) document files. The default program is Internet Explorer.
html - HTML (Hypertext Mark-up Language) document files. The default program is Internet Explorer.
ico - Icon files. The default program is Windows Photo Viewer.
img - CD or DVD image file, essentially equivalent to an ISO file.
inf - Setup information files. The default program is Notepad.
ini - The INI file type is primarily associated with 'Initialization/Configuration File'. These files are typically ASCII text with various configuration options set into sections.
iso - Image file.
jnt - Journal document file. Default program is Windows Journal.
jpe - JPEG (Joint Photographic Experts Group) image files. The default program is Windows Photo Viewer.
jpeg - JPEG (Joint Photographic Experts Group) image files. The default program is Windows Photo Viewer.
jpg - JPG (Joint Photographic Group) image files. The default program is Windows Photo Viewer.
js - Java Script files. The default program is Microsoft Windows Based Script Host (C:\Windows\System32\wscript.exe).
library-ms - Library folder.
NOTE: To restore the default icons, you may need to do these as well.
lnk - Shortcut link (LNK) files.
log - LOG is a file extension associated with Log files. It is a text file.
M2T- High-definition video recording format used by many HD camcorders; commonly referred to as "HDV;" uses MPEG-2 compression to store HD video data on DV or MiniDV tapes; supports resolutions of 720p and 1080i.
M2TS - Blu-ray BDAV Video File. Video file saved in the high-definition Blu-ray BDAV format; used for saving video data on Blu-ray discs; based on the MPEG-2 transport stream and supports 720p and 1080i formats. BDAV stands for "Blu-ray Disc Audio/Visual," while the M2TS extension refers to "MPEG-2 Transport Stream."
m3u - The M3U file type is primarily associated with 'MP3 Playlist File'. Generally known as a "Winamp" Playlist file, this format has been adopted by a wide variety of MP3 players. The default program is Windows Media Player.
M4V - MPEG-4 file extension used for videos downloaded from the Apple iTunes store; includes TV episodes, full-length movies, and music videos; similar to an .MP4 file, but may be copy-protected using Apple's FairPlay DRM copyright protection.
mkv - A Matroska Multimedia Container file is a video format similar to the .AVI, .ASF, and .MOV formats. By default Windows 7 does not have support for opening this file type and has no association.
DivXPlayer is a good free program to install that does support playing this file extension. This download will set this file extension back to the default unassociated state in Windows 7.
mov - Movie file. The default program is Windows Media Player.
mp3 - MP3 sound format file. The default program is Windows Media Player.
mp4 - MPEG-4 movie file. The default program is Windows Media Player.
mpa - MPEG audio file. The default program is Windows Media Player.
mpe - MPEG movie file. The default program is Windows Media Player.
mpeg - MPEG (Moving Picture Experts Group) video file. The default program is Windows Media Player.
mpg - MPEG video file. The default program is Windows Media Player.
msc - Mirosoft Common Console document files.
msi - Microsoft Windows Installer installation package file.
msp - Microsoft Windows Installer Patch file.
MTS - MadTracker 2 Sample File. High-definition MPEG Transport Stream video format, commonly called "AVCHD" (Advanced Video Codec High Definition); used by Sony, Panasonic, and other HD camcorders; based on the MPEG-2 transport stream and supports 720p and 1080i HD video formats. MTS files can typically be opened and edited using the software included with Sony and Panasonic HD camcorders. The default program in Windows 7 is Windows Media Player.
otf - Open Type Font file. The default program is Windows Font Viewer.
Package - Package protocol.
pbk - Dial-Up Phonebook file. The default program is Remote Access Phonebook.
pdf - Portable Document Format (PDF) is a file format created by Adobe Systems. By default, Windows 7 does not support reading this file type. Using this to restore the default PDF association in Windows 7 will remove all associations for the pdf file extension. You will need to install a 3rd party program like
Adobe Reader or
Foxit Reader to be able to open and read pdf files in Windows 7.
png - Portable Network Graphics (PNG) is a bitmap compression method for image files. PNG supports 16.7 million colors, it is lossless and also supports index color, grayscale, true color, transparency, and is streamable. It is thus the best compression method (better than GIF or JPEG) for use on the web.
ps1 - Microsoft Windows PowerShell command line shell and scripting language file. The default program used to open with is Notepad.
psd - The PSD file format, created by Adobe, contains graphics/photos created by image editing software such as Adobe Photoshop.
reg - Registry file.
NOTE: You may need to set the default program as Registry Editor (C:\Windows\regedit.exe) for reg file extensions, or enable regedit before you will be able to use this REG file.
rtf - Rich Text document files. The default program is WordPad.
scr - Screen Saver files.
tar - Tape Archive file. By default, there is no associated program for this in Windows 7.
themepack - A .themepack file is a
Windows Theme Pack file.
tif - Tagged Image files Format. The default program is Windows Photo Viewer.
tiff - Tagged Image files Format. The default program is Windows Photo Viewer.
tmp - Temp file. By default, this file extension does not have a program associated with it.
TS - Video Transport Stream file used for storing video on a DVD; compresses video data using standard MEPG-2 (.MPEG) video compression. TS files are often saved as multiple files on a DVD, i.e. "moviename1.ts," "moviename2.ts," "moviename3.ts," etc. They can be played back by various software DVD players and video editing tools
ttf - True Type font file. The default program is Windows Font Viewer.
TTS - A .tts file is a text file (an ini file) that corresponds to your book. The ToolBook Translation System (TTS) creates the .tts file for you when you set the book's TTS Identifier through the Setup Sources window.
txt - Text document files. The default program is Notepad.
url - Internet website shortcut link. The default program is Internet Explorer.
vbs - Visual Basic Script files. The default program is Microsoft Windows Based Script Host (C:\Windows\System32\wscript.exe).
vob - Movie data file from a DVD disc, typically stored in the VIDEO_TS folder; contains the majority of data stored on the disc including video, audio, and subtitles; usually formatted as an MPEG-2 system stream and can be opened by various video playback programs.
wav - Wave audio file. The default program is Windows Media Player.
wma - Windows Media Audio files. The default program is Windows Media Player.
wmv - Windows Media Audio/Video file. The default program is Windows Media Player.
wsf - Windows Script Files. The default program is Microsoft Windows Based Script Host (C:\Windows\System32\wscript.exe).
xml - Excel Macro files. The default program is Internet Explorer.
xps - XML Paper Specification document files. The default program is XPS Viewer (C:\Windows\System32\XPSViewer\XPSViewer.exe).
xsl - A eXtensible Stylesheet Language file that defines the style of text, tables, and other objects within a XML document; similar to a .CSS file used by .HTML documents. The default program is Internet Explorer.
zip - ZIP file extensions is a archival and data compression format used to compress one or more files to reduce the size of the file. The default program is Compressed Folders.
