if you opened the phone, there‘s the possibility that the display connector isn’t plugged in properly or you damaged the display by accident during the opening procedure. Try to open it another time and control if the connector is plugged in properly. You can check if the display is working before reapplying the back cover with anew adhesive. In case I didn‘t get you right, and you did not open the phone, it is likely that your display is broken because of water damage or similar. In this case, you need to replace the screen. The vibration motor is still working because it isn’t connected to the display but to the daughterboard.
!&&* Zero,
if you opened the phone, there‘s the possibility that the display connector isn’t plugged in properly or you damaged the display by accident during the opening procedure. Try to open it another time and control if the connector is plugged in properly. You can check if the display is working before reapplying the back cover with anew adhesive. In case I didn‘t get you right, and you did not open the phone, it is likely that your display is broken because of water damage or similar. In this case, you need to replace the screen. The vibration motor is still working because it isn’t connected to the display but to the daughterboard.