wont turn on or charge

First thing you might try is to use another USB cable. Check the dock connector carefully for any bend, broken, corroded pins and debris. Clean it with isopropyl alcohol and a toothbrush, or similar tool. After that, try an AC charger. It is easily possible that your battery is at the end of its lifecycle. Replace the battery first, then re-evaluate and see what you have. Follow this guide for the repair and the battery is available right here. Hope this helps, good luck