My Iphone5 has a black screen and won't turn on

So after school one day i took my phone out of my pocket and the screen was black, i was pressing the on and off button for the sound and i could hear the noises, so i decided to restart my phone. After waiting for ten minutes i keep on pressing the restart button and it still would not turn on. Once i got home i plugged my phone into the charger thinking that it might turn on. However it just kept on making the noise as if i was pluging and unplugging the charger repeatedly. I keep on restarting the phone and it still has not turned on. It has been two days and the phone has still not turned on. When i plugged my phone into the the computer thinking i could reset my phone into facotry settings, itunes could not recognized my serial number. Now after not charging it for a day it will not charge at all