Have you ever been able to listen to the files??
What Media Player are you using. If Limewire Player, see if you have it checked. Limewire Player will only play Audio files. No Video files
Go to Tools > Options > Player. Make sure there is a check in the box. Press Apply and then OK.
What file extensions are you trying to play?? i.e. mp3, wma...
Make sure you scan ALL files with a Good Antivirus Program before you open them.
I will suggest trying VLC Media Player. See VLC Player within this thread.
CODECs list for Movies/Audio/ Alternate players / Video help forums/ video-mp3 fixers
Hope this helps.