There are 2 options:
1. The files have been converted.
2. The files are the same as they were but a setting has been changed so they are only PLAYED with the other program.
I think it's #2. Real Player and wmp aren't file formats, it are programs. In that case, all you've got to do is change the file association for those file types back to WMP, and everything is fine again.
1. It depends on your OS (Windows 98, ME, XP, Vista, 7) how exactly to change the file association from the OS.
2. And it depends on the version of WMP how to do it in the options of WMP.
3. And it depends on the file types (the extension, that's the part of the filename behind the last dot) WHAT file types to change.
So, power user or not, those are things you've got to find out to get more help. #2 might be the easiest way.
Somehow my personal videos all got converted to Real Player. Is there a way that I can convert them back to wmp? I have many, so it would be good if I could convert them as a group.
Hope I have made myself clear as I am not a power user.