Macs can read the Windows disk format, but Windows PCs cannot read the Mac disk format. Doing a Restore on a Mac made the iPod unusable on a Windows PC, until you do another Restore on the Windows PC.
If it does not get recognized by the Windows PC when connected, try putting it in Disk Mode first
Run iTunes on the Windows PC and connect iPod to a direct USB port. iTunes will probably prompt you to do a Restore.