That happened to my sister, actually. She had somehow managed to get a trojan or virus of some sort that really messed up her music folder. I was unable to fix it, so I had to FDISK the machine and reinstall windows.
Did you back up your music collection on CDs or DVDs before this issue?
Something to consider before you do anything is to DL someting like Damn Small Linux
I've got more ideas if you need them. and boot to the Live CD. What this does is give you an OS that runs off of a CD, never touching the existing Windows installation on your hard drive. That way you can try to access your music without whatever made windows freak out getting in your way. It's worth a shot.
