Sounds like screen failure or graphics chip failure.
something to try
Power off remove battery and mains lead
press and hold power button for 30 seconds
connect mains lead and see if it will start up.
Check the lid switch isn't stuck down.
Next you need to connect to a external monitor / TV with a VGA cable and use the FN + F? key(with blue square) to cycle through screen options (LCD - external LCD+External) worth trying cycling with out another monitor.