Rosie, could b a bad battery or a bad cable as well as a bad dock connector:-) Try to check the dock connector first. Make sure there are no brokenm bend or corroded pins. Clean it with some isopropyl alcohol and a few puffs of air. Pocket lint can prevent it from charging:-) If it is clean, try a different cable. If that does not help, it may be time to disassemble it and to replace the battery. Follow this guide to get it accomplished. Hope this helps, good luck.