Try turning it off... then connect an external monitor to it. Turn on the Monitor FIRST, then turn on the laptop.
Does your regular screen show on the external monitor? If try updating the drivers, then reboot without the external monitor plugged in and see if it works. If it doesn't, then the laptops display needs replacing.
If, when you load it (the first time) with the external monitor plugged in and nothing shows on it either, then the graphics card is probably needing to be replaced.