My iPhone screen is dark but seen under a bright light

I dropped my phone from 2ft onto the floor and the screen went black but I could hear it locking and unlocking so I knew it was working, so I hard reset it and it started working fine again. Then overnight it went dark again and I had to hard reset it again when I woke up, and then I set my phone down on a table and when I picked it up it was dark again. This time when I hard reset it the screen just flashed white. Since then my phone screen is so dark and the only way I can see anything is with a flashlight. I've done a full reset of the phone, and the touch is working. I can answer calls and do everything I normally do on my phone as long as I'm using a flashlight to brighten the screen. The phone is in perfect condition, there's absolutely no physical damage to it and I have never dropped it in water. I have dropped the phone here and there but always with a case on it so there has never been any physical damage. Can anybody tell me what's wrong with my phone because I've tried taking it to stores in India and they say either the screen needs to be replaced or the whole phone, but my phone is worki as normal just the backlight seems to be gone. Please I'm desperately hoping that the max is that I have to replace the screen which is expensive in India but almost half the price in Dubai which is doable.