Sometimes, when software is installed, the software changes the programs that are used to open certain file.At times, this is not desired because the new software may not be able to open the files. In order to restore the settings, the file extensions must be re-associated to open with different software programs.
Step 1: Open 'My Computer'
Step 2: Click 'Tools' (at the top menu)
Step 3: Click 'Folder Options'
Step 4: Click the 'File Types' tab
Step 5: Locate the file extension you would like to change
Step 6: Click 'Change'
Step7:
Select a program on the list OR click 'Browse' to search for the installed program that you would like to use to open that file extension.
Step 8: Click 'OK'
Step 9: Click 'Close'
Step 10:
Test the extension by double-clicking on a file with the extension that you re-associated the file with.