So I just got my iPhone yesterday, It has been used but it is in good condition. I accidentally banged it into a chair when I was getting up from my seat ( i was holding it ) and it dropped on the floor. The screen isn't cracked or broken, my problem is that I cannot unlock it. When I touch the screen it does not activate. The top part of the screen does? ( when i was turning it off it let me scroll the bar for it to shut down ) I don't get it. I can't use my iPhone because it wont let me unlock it. I tried restarting it, it doesn't work. I have no dents or anything on it. Help me? Any suggestions?