LCD malfunctioning with a fully working touch screen glass screen

I recently dropped my iPhone 7 on the floor with the back facing the floor. When I lifted it up its shape seemed to be fully intact , it`s LCD was malfunctioning ( It seems as if the upper part of the screen is working but reflecting the lower part of the screen at the same time; there is a crack beneath the glass screen and not on the screen that can be seen when the phone gets lit up) and its glass screen was fully intact. I was able to use all the function on the phone including touch screen, camera and listening to music .

After a few inspections on my phone, I realised it is very slightly bent ( almost impossible to see). The phone`s LCD sometimes works ( the image can be perfectly seen but there are transparent lines going throw it and the crack still stays) and soemtimes doesn`t ( the upper corner of the screen has coloured lines going throw it and the weird reflection can be seen again).

What happened? How much does it cost to rapair? Shpoul I repair the phone?