there is a crack but no crack

i dropped my phone onto the carpet and when i picked it up it wouldnt turn on. i looked at it a seen what looked like cracks but they looked like a video game kind of like crack that is behind the screen. i plugged the phone in and it started charging but the display didnt come one. can someone tell me what is wrong and what do i have to replace and if so how do you think it will cost?here is a link where u can kind of see the cracks

http://imgur.com/Jc6OB0W