i have an ipad first generation that ive taken really good care of. it hasnt given me any problems until now. i was on the internet on my ipad and the screen just went black. i thought the battery just ran out and i plugged it in to a wall charger and nothing happened for half an hour. then i tried to restore it on my computer but the computer cant pick it up and under "device" nothing is listed. please help. thank you!