Why isnt my iPod charging

The battery may need to be replaced. ipods will not turn on until the battery has exceeded a certain threshold value for being charged. Every battery has a limited number of recharge cycles ~500 (varies) before they need to be disposed.

If the battery is ok it could be the charge cable or the charger itself that is causing problems. Ipods check for resistors or resistance levels built into third party chargers to identify if it's an apple made/ approved product. If this doesn't jive for some reason or other, the ipod will reject the charge all together.

Try switching charge cables/chargers amongst friends to see if you get better results. You can bring it into an apple Genius bar and let them try to reset it too. Tell them that you think your charger needs to be replaced but you wanted to verify it with them before making the purchase.

btw you may want to edit your post to show which make it is... for example newer models do not like fireware based chargers

Cheers.