Reconnecting my music files to iTunes 11

I had to reformat my system drive on my pc and reinstall Windows 7 after a devastating virus. I had backed up my library of songs, (over 21,000 to a second drive. I have re-installed itunes 11 and routed it to the backup file using the advanced tab section. The problem is itunes doesn't see the songs. It only sees purchased songs but not the songs I ripped off of cds (album, song, artist mode). However, the playlist show up but if I try to play a song I have to manually locate the song to get it to play. I don't want to do this for 21,000 songs. Is there a way to get itunes 11 to re-link to the song library I had made a back up to? I appreciate any good advice on this matter.

The cds were ripped using itunes 10 but I had already updated to itunes 11 and made the back up from itunes 11.

Thanks,

Yemir JR