Is the operating system recognising it? Does it show up in My Computer or the Desktop if you're on a Mac?
If yes, and the charge didn't solve the problem, try giving the iPod a hard reboot by toggling the hold switch on and off and then pressing and holding the center button and the menu button simultaneously. If that doesn't sort it then if you look in your iTunes/iPod software folder there should be a small programme that can update the software or restore it to factory settings.