- If you previously turned on FIndMyiPod and wifi is on and connected go to iCloud: Find My iPhone, sign in and go to FIndMyiPhone. If the iPod has been restored it will never show up.
- You can also wipe/erase the iPod and have to iPod play a sound via iCloud.
- Change the passwords for all accounts used on the iPod and report to police
- There is no way to prevent someone from restoring the iPod (it erases it) using it.
- Apple will do nothing
The only way to find a lost iOS device is to use the Find my iPhone app or www.icloud.com. For this to work, you have to enable this feature on the lost device prior to loss. If you didn't do this, there is no way to find it. Neither Apple nor your carrier will find it for you.
Setup Find my iPhone:
Here's a good tip from Kappy on what to do if you device is lost or stolen: