Inside of Windows 7 and Vista, file extensions are iffy… at best. At times file extensions will lose association, start opening in odd programs, icons changing and more. And when the context menu is able to change the default program, a lot of things can still go wrong. Luckily a developer out there has a fix.
There is a script/program by Ramesh Srinivasan of TheWinHelpOnline.com called Unassoc. It does exactly what the name says, Un-associates file extensions. This program is free, portable, single executable and very simple to use. I have used this program so much to resolve issues, I can’t thank him enough, and thought I would share it with all of my readers.
How I Use Unassoc
The main reason I use unassoc for is to fix the missing or incorrect icons for file extensions. I know this is somewhat a pointless thing to fix, but I have OCD when a CSS file shows it’s going to open in Notepad and then opens in some random program, or when C source files say they are going to open in Sublime and then open in Microsoft Visual Studio. The reason this happens for the most part is that each program names the extension something different, like C Source, C Programming Source, C File, and so on. The registry looks up the first C extension and grabs the file that is associated with that, even though it may have a different default opening method.
Other ways to use the program is for cleaning up File Types, or getting rid of File Extensions from the registry that you will no longer use. You can also see a list and search through all the file extensions and types you have.
Make sure you download unassoc.zip and extract it. You will require administrative access to use the program because it is modifying the registry.