Try connecting it to your computer that is running iTunes. While it is connected, do a Reset on the iPod.
http://support.apple.com/kb/HT1320
Does iTunes recognize it in any way?
If that does not work, do the same thing, but put it into Disk Mode while connected to the computer.
http://support.apple.com/kb/HT1363
Does iTunes recognize it in any way?
If iTunes does recognize it either way, see if you can select the iPod in the iTunes sidebar under DEVICES and use the Restore button that is on the iPod's Summary tab (over to the right). This will erase the iPod, re-install the latest software, and set it to default settings.
If iTunes does NOT recognize it (or if doing a Restore fails), it is possible that the hard drive in the iPod has become faulty. Quit iTunes and see if the iPod is seen as a "disk" by Windows (or if it appears in device manager).