The easiest way to locate your iPod Touch 5G if it got lost or stolen is to log into iClouds and click on the “Find My Phone” link. This will display a map and show where your phone is, but only if you have previously connected to iCloud and enabled this feature on your iPod Touch. You can also erase your data on your iPod as well through this connection if you are afraid your personal information will fall into the wrong hands.
If you had not enabled that option, then calling the police and Apple and reporting it stolen is your next best option. You will need a serial number for that and if you don’t have that recorded anywhere you can look it up on your iTunes account. Apple will be able to tell if your iPod has been used or not since it was lost or stolen.
Source Apple Store