My ipod touch was working perfectly fine. I plugged it into my computer with a usb and it was charging. It charged all the way and i left my ipod on as well as the computer. I came back a few hours later and tried to use ipod. I got nothing it will not power on at all. I held the power and home button for 10 seconds and that did not work. The ipod is showing no signs of life. Can you tell me what to do. Any advice is greatly appreciated.