they must have restored your ipod. please connect your ipod to itunes, and click on the ipod, now you will have to set it up (as a new ipod), or try to see if itunes saved a back up like it should. heres how.
Plug your device into your computer an open iTunes. Right click on your device in the the key sidebar, and select the 'Restore from Backup' option.
Place the iOS device in Recovery Mode and then connect to your computer and restore via iTunes. The iPod will be erased.
If recovery mode does not work try DFU mode.