Is it just the display that isn't working? or is the whole thing not turning on? If it is just the display try turning the laptop off, connect an external monitor to the laptop, turn on the external monitor and then turn on the laptop. If you can see your screens on the external monitor, then the problem is with the attached display. You would then need to check the ribbon cable that connects the display. Should that be fine, then the display itself may be gone.
However, if there is nothing showing on the external monitor either, then your graphics card/GPU will probably need replacing (which may need the motherboard replaced to fix).
NOTE: Before doing anything to the laptop, if your device is under warranty still, contact the...