What Belodion linked to is definitely a defective (probably physically broken inside) screen. If that's what yours looks like, in gray, on the entire left side, it's new screen time. (And please don't try replacing it yourself. Regardless of how easy it looks in the videos, most of those people have already done many screens, and probably broke a few phones learning how to do it. I found, when I owned my stores, that it took between 3 and 6 tries before a tech with no prior experience could replace a screen without causing a problem. Even pinching the wrong wire against a metal frame can blow a motherboard.)