If your iPod keeps restarting, but won’t start up all the way, it could be because of any number of reasons. The best thing to try first to make sure you don’t lose any settings or data is to turn your iPod off and allow the charge to completely drain. When the charge is drained, recharge your IPod for at least an hour and then try to restart it again.
If upon draining and then restoring the charge to your iPod doesn’t force it to restart properly, you may have to restore the iOS. You will lose data this way, but if you have been backing up to iTunes or iCloud then you can restore that data after your iPod is working again.
To start the restore process for your iPod, open iTunes and connect your iPod to your computer and select it in the iTunes navigation. When the Device comes up, choose the Summary tab and click on “Restore”. If restoring your device doesn’t work, then you need to contact Apple Support to see if you might be having any hardware issues.