Black or dead screen

what I recommend you do first is to plug an external monitor into your computer. If the external monitor works, you know that your motherboard/GPU works and you can concentrate on the LCD. If you shine a light i.e. flashlight across your screen and you can see the outlines of your desktop, just very dark, you know its the backlight or inverter of your LCD. If you move the screen slowly up and down and you see lights flickering etc. it's your cables. You will find out more when you trouble shoot it one step at the time. If you need to replace the screen, the guide for it is here. Most likely it’s either bad inverter or failed backlight lamp. You cannot tell which one is bad until you test the laptop with a known good inverter. If I would have to guess, I'd replace the inverter board first. It’s easy to access and replace, and it shouldn’t be very expensive. Hope this helps, good luck.