Katerina, check the dock connector (the part on the bottom where you plug your cable in) make sure that it is clean, no dust in there, that the pins are not broken, bend or corroded. Clean it with some isopropyl alcohol and a few puffs of compressed air. after that, try to charge it from an AC adapter, not a computer. If none of that works, you might consider changing the battery. Follow [guide|9829|this guide] to get it accomplished. Hope this helps, good luck.