Bad restore of iPod Nano 4th gen

This morning I tried to restore my iPod Nano 4th generation.

Everything seemed to proceed in the right way: I followed the procedure, iTunes downloaded the newest software, but after some seconds an error occurred (in the range of 1400, actually I don't remember the exact number).

From that moment, iTunes doesn't see my iPod anymore, and it's present only as a generic disk in the desktop.

I tried to restore it also from the Disk Mode, but again iTunes didn't see my iPod.

Can I do something to fix this problem?

Thanks!