Lenovo G550 screen



I own a G55O Lenovo laptop. My screen suddely stopped working, there is no crack, oly tht I can't see whats going on. The rest of the computer works. When I plug it into a desktop computer can see my screen. What do I do now? Do I buy a new screen?
its possible the inverter has gone bad or the screen itself has gone out. I would suggest replacing the inverter first, this would be the cheapest route, if that does not work, then replace the screen. if you can see it fine on an external monitor, then your video card is fine.