Have you tried resetting the iPod?
Turn the Hold switch on, then off again and then press-and-hold the Menu and the Select (centre) buttons simultaneously for at least ten seconds. During this time, the Apple logo should appear and the iPod will reset. Apple recommend that you place the iPod on a flat surface while doing this (makes it easier to press the buttons) and that you try this up to three times before deciding that a Reset will not work.
If a Reset doesn't work, it's possible that the iPod is "stuck". In this event, leave the iPod unplugged for a few days and wait for the battery to run down. (Obviously, there's an element of guesswork about the length of time this takes.) Then plug the iPod into a power source in order to recharge it.
If the iPod is stuck in a task, then once the battery has run down, then there will be nothing doing whatever it was that caused the iPod to stop responding. When the iPod is subsequently charged, all the "switches" that control the iPod are set back to a start condition. Once that happens, the iPod should work. It can take up to thirty minutes after plugging in before you see any response from the iPod. Wait for it to fully charge.
