Iphone 4 will not turn on

My iphone 4 will not turn on. I was using it then it froze, so i tried to shut it off and it didnt do anything. So i held down the Power and Home button until the apple came on. When the apple came on it told me to plug the iPhone into itunes, so i plugged it into itunes and it extracted the software then gave me an error. Now wen i plug my phone into the computer it doesnt recognize it. It is completely dead. NOTHING works, ive tried to hold the Power and Home for 10 seconds and even longer but nothing happens. PLS HELP...