I've had this this phone for 2 years my galaxy S7. For some reason it started glitching half of the screen goes gray then it goes dark. I restart the phone and it gone but recently it dose it more. I have not drop my phone or damage it. It's the only phone I have at the moment. Anyone knows what may cause this to happen or it time to get a new one? I hope its fixable because I don't have the $ to buy a new one.
It looks like a system bug.
Try to perform a factory reset ( turn off your phone - press Power + Home + Volume UP - wait some seconds - scroll by volume button to wipe data/cache and press power button to select, confirm it )
If it didn't work, try reflashing the stock firmware by Odin or Samsung Kies.