iPod Nano not being recognised

My moms new iPod nano had been connected to our iMac for a few days while she was sorting out her library in iTunes, so it was fully charged this morning and I wanted to sync it for her. However, it wasnt in iTunes nor in Finder so I disconnected it, no errors so anyway, I connect it again (via usb) and nothing happened on the mac, only the iPod said that it wal charged.

I tried resetting the iPod but it made no difference, I also tried a brand new iPod cable. Its not in Disk Utility either. I googled it but cant find much or none of it works, what do you do if something like this happens?

It sounds as if you've tried most everything possible. Call Apple.