Why isnt facetime camera working

so i have a iphone 5 that was working fine a couple days ago then i was on snapchat and the front facing camera didnt work so i took the screen off and connected it back on and it worked until i closed the camera app so i reset all settings and it didnt fix it so i updated the phone and reboot and everything is the camera bad i dont know if its that cause wouldnt all parts be bad cause i can hear people on the phone and the sensor works just the camera doesnt respond and i just tried facetiming someone to see and it was just a blank screen any ideas