hi
its a common problem im afraid. You could try a reset first - hold down the play/pause button and menu button at the same time for 5 seconds.
if that doesnt work..... If you plug the ipod into your PC does it recognise it? If it does, try this.....
Go into start up -your programmes.
Select IPOD
Go into the Software Updater file
This will search for the IPOD as a hard disk
A screen will pop up asking you to RESTORE.
(This will erase everything you had on it, not a problem as you can update later from your existing ITunes Library.)
As soon as the restore has completed.
Plug the IPOD directly into your mains power adaptor via the firewire it came with....as if you were going to do a charge from mains.
This will display a progress bar and complete.