Hi, all of a sudden today when I look at my phone, the screen is black and none of the keys respond. I take out the battery and put it back in no response. I repeat at least ten times, and same thing. I call my phone from another phone, and the call comes up on the screen, but when i try to click send, end, any other key, there is no response and when the call ends, it goes to the home screen and sure enough fades back to black. Battery is fully charged, and I have no idea what is wrong with it. It is a 8330, and I need my phone to work asap. I have sprint. Thank you in advance.