When you double-click on a file the program uses the Windows API ShellExecuteEx to 'launch' the file. At this point you're in the hands of the Windows Shell.
You've probably recently installed a new program that effects the registration of those files types. Run the 'Default Programs' settings app and see if that can fix the registration for the effected file types.
To test whether or not this effects ALL file types try double-clicking on a Text (
.txt) file or a picture file (e.g.
.jpg) and see if you get the same problem.