iphone 4 with black screen

i dropped my iphone 4 onto a gym floor with about a foot of a drop. it has a lifeproof case on it. as soon as i picked it up to check it, the screen was completely black. but the screen still lit up but it was black. Its be vibrating from getting texts. its been about two hours now and it hasnt done anything. ive tried doing restarting it. ive tried plugging it in and restarting it.. ive tried plugging it in to itunes but it tells me that to use the iphone i need to enter a passcode on my phone so i can restore it. so i guess that wasnt much help. what should i do next or how can i get it to restore without unlocking my phone