My iphone 4 screen will not turn on but I can still hear my ringer?

My iphone 4 screen will not turn on but I can still hear my ringer?

Added (1). My iphone 4s screen will not turn on. I can still hear the ringer and it will still vibrate whenever I get a message, call, or email. If you have a solution for this please let me know. Also, I can't use my lock button because it is broken and stuck down. I did not drop it and don't know why it is doing this.

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