Do you have an HDMI or VGA cable connected to another monitor?
Try HOLDING the Fn Key and then pressing F8 and see if it comes on.
If not you can try HOLDING the Fn Key and then press F7.
There is also the possibility that the ribbon cable to the LCD is loose. A drop of the laptop would easily unseat this connector.
You'll have to disassemble the laptop if the cable is loose. Click
HERE for the procedure.
If you aren't comfortable with repairing the laptop yourself then your next option is an ASUS Repair Center. Find the closest one to you
HERE.