@enochboateng without seeing it but going by your description and knowing this happened right after it got dropped, it sounds like a bad display. SInce iFixit does not yet have a guide for this, use some videos [https://www.youtube.com/watch?v=FQCB_eeqgU0|like this] or even [https://www.youtube.com/watch?v=DMeC7YuVw1o |this one}. Replacement displays are readily available at many online stores. Pick a vendor that appeals to you.
While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.