I am having Nokia lumia 920. Sometimes my phone's screen does not work. I pressed the unlock key but it does not makes any difference. Keys blink for few seconds and goes off again. Then when i tried to call it from another cell it worked and display worked fine. It has happened two times in previous three days. It is worrying me please suggest me. I have Black software update in my phone but the problem is similar to this Thread. Also my phone's info is here in the image.!