You need to replace the AMOLED screen assembly. Apparently when you dropped the phone, the digitizer beneath the glass cracked in addition to the outer glass lens. You can find a replacement assembly here:
https://www.ebay.com/itm/LCD-Display-Touch-Screen-Digitizer-For-Samsung-Galaxy-J6-2018-J600DS-J600F-J600G-/192854032646?_trksid=p2385738.m4383.l4275.c10&var=492988081475
Hope this helps