Welcome to the forums.
You should back your mp3's up
Download winamp, from www.winamp.com
After installing it right click the mp3 file and select open with. Make sure the "open with" option is NOT selected. Scroll down the programs until you come to winamp, and open the mp3 with winamp.
I'm almost positive that the mp3 will work with winamp, so if it does, just use winamp.
P.S. you could also use windows media player