Media Player cannot find the file

I am operating Media Player Version11.0.5721.5230 on Windows XP service Pack
All of a sudden, none of the .wma song files will open when I try to play
them, and the message below appears:
Windows Media Player cannot find the file. If you are trying to play, burn,
or sync an item that is in your library, the item might point to a file that
has been moved, renamed, or deleted.

Any help would be appreciated