urgent please

well i was in the library studying from my macbook 13 inch retina display , after i finished , i put it in the bag that i bought from apple online store , i went back to my dorm and i found that my screen is cracked i am assure that i didn't bump into something , but i know this won't help so i want to know the estimated price for the retina display screen 13 inch does anyone knows how much does it cost \?