It's a long shot but it may work
Obtain a recovery software, R-Studio has worked for me, but there are several on the web.
Connect the IPod, CLOSE ITunes, open My PC, you should see a removable disk, that's the IPod.
Open it, if there are folders named like 01,02, etc open one of them, if you find some files with strange names, leters with no meaning, your music is still there, just copy the files to your computer.
If that's not the case do the following, using the recovery tool try to recover the music from the removable disk INTO your COMPUTER HD.
And a last advice always keep your music on one computer and only use one computer with the IPod
