Corrupt IPod classic

I have a 120gb iPod classic which had over 2000 songs on it. Most were loaded from CD’s which I no longer have, a few were from iTunes. The iPod is now saying it is corrupt and there are no tracks on it, I have tried various recovery software types and despite finding folders all are empty! I believe that files on an iPod are never deleted but are hidden, does anyone know if this is correct and if so how do I recover my music. Thanks in advance