@senopatib could be a battery issue. If this battery was discharged beyond the charging threshold it will no longer accept a charge. It could also be that there are issues with the charging cable or the dock connector. Check that one for broken, bend or corroded pins. Of course, you also want to double check your work to make sure everything is properly connected. The other thing you want to try is to charge the iPod with a wall charger instead of your computer etc.