Electronics Repair Questions? Ask an Electronics Technician
If you can still take photos and they appear ok on a computer, but you cannot see anything on the on-screen display, even the settings menu, then it is likely that either the display ribbon cable has come loose inside the camera, or the display has failed.
To fix this, you will need to open the camera up and check the display ribbon cable is securely attached first. If it has come loose, re-attach it and apply some glue to help keep it in place.
If the problem is not caused by a loose display cable then the display itself is suspect and will need to be replaced.