Right now I would start off with trying to charge a battery with a wall charger, not' your USB port. It is possible that the iPod is totally discharged. If it does not charge, check the cable, and the dock connector as well. If that is all okay, consider getting a new battery, if charging from a wall adapter remains unsuccessful. Also, try to restart your iPod by:
" Press and hold the Sleep/Wake button for a few seconds until the red "slide to power off" slider appears, and then slide the slider.
Press and hold the Sleep/Wake button until the Apple logo appears."
Hope this helps to get you started, good luck.