iPhone 5s black and white strips appear on screen 16 GB ios 8.4

I have a IPhone 5s 16 GB, today i noticed that the screen showed vertical black and white stripes. I thought if i rebooted my device it would go back to normal but when i rebooted it all my phone was showing is a black screen. My phone charges and connects to my pc, i wanted to back up my phone but when i tried it said "backing up" then went away after a few seconds. i have a lot of disk space left in my pc. so if you know how to fix the black and white strips and the backing up issue i would be grateful if you can help me!