Touchscreen bugged and display only in grey colours.

I have an Iphone 5c with a screen protector and I have dropped it numerous times. The touchscreen had been slightly buggy and unresponsive for a while, but the problems could be fixed by quickly turning the phone off then on again. About 4 weeks ago my friend dropped it and clear lines appeared flickering horizontally across the screen. They almost resemble rainfall in a pixel game. The lines remained for a while until I dropped it again and now the display only consists of a palate of greys as if I had turned on greyscale mode. I have tried turning greyscale mode on and off again to no avail. I have gone into the zoom function and ensured there are no settings that could activate greyscale. Sometimes by powering off and on again the "greyscale" changes back to the lines from the initial drop. But it reverts to the current state after a little bit. The touchscreen is also very glithcy and unresponsive, forcing me to turn my phone off and then on again (almost every single time I go to enter my password!). Apart from the buggy touchscreen and the glitched out display all the other features work. Does anyone know what I can do to fix the touchscreen and the display?