Yesterday, I was using my phone (droid 3) and the app I was using force closed, my phone lagged for a few seconds and then I just put it down so it could catch up. While waiting the screen timed out and when I went to use it I could not unlock it. I can press the button on top and it will turn the screen on or off, and if I hold it it will bring up the power off menu. I tried to call it, and it went through. I got the normal screen to answer it, but I could not answer it. After I hung up I got the notification for a missed call. Everything seems to be working, my screen just does not respond to a touch. What should I do?