The solution is simple just hold the home button and the power button about 15 seconds and it will show the apple logo with means its rebooting while its rebooting hold the home button while connecting usb cable and remember to open itunes before doing this after this later it will ask you to restore the ipod.
Restore loop (being prompted to restore again after a restore successfully completes)
Troubleshoot your USB connection. If the issue persists, out-of-date or incorrectly configured third-party security software may be causing this issue. Please follow Troubleshooting security software issues. .
Next try placing in DFU mode and then restoring.
Then try restoring on another computer.
Last, make an appointment at the Genius Bar of an Apple store.