No display after being dropped on iPhone 5C

There is no display on iPhone 5C after being dropped. The phone is on because I can switch the vibrator switch and it will vibrate. I tried a known working LCD with the same results, no display. At first, I thought it was just this particular phone but in the last week I have seen 2 other iPhone 5c's with the same symptoms. They were dropped and now no display. The screens on the latest 2 phones was not broken and there are no signs of a cracked LCD. What could be the possible cause of this and what can be done to solve the problem?