The top part of may screen is not working

@manasseaku49369 that means that you have a broken display. There really is no repair for it but you will have to replace the display. Since iFixit doesn't yet have a guide for it, use the one from here It was written in French but your browser should translate it without any issues. Replacement displays for your model are readily available and many online place, Just make sure that you get a replacement for your particular model.

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.

Repair is War on Entropy!