iPod Classic not recognised in iTunes - asks for restore

Hi guys

160 GB Classic iPod is full and working fine yesterday.

Today it says it has no music (despite being full as shown in settings) and when I connect via my Mac, iTunes says it cannot recognise and I must restore.

This will be a massive pain as a lot of the music on iPod was on a broken hard drive.

So how can I fix?

Tried basic stuff like reset

Thanks

Nick