You will need to get the whole screen replaced more than likely. however sometime though very rarely the ribbon cable for the screen shifts off the board and you get this type of issue. either way you need to open u the phone and look and try reseating the ribbon cable. if that doesn’t work you just need a new screen and honestly the disassembly is the hardest part.
you will also need to get some double sided tape I like to use the non conductive type and you can get a set of 4 rolls of various widths from amazon.