How to fix black screen?

@wisdomyevugah you have not told us what you have checked. The no video issue can be related to a bad backlight inverter circuitry. A simple check for that would be to darken the room and turn the computer on. Then use a flashlight and angle the light at the screen on different areas. Check to see if you can make out some shadows from your desktop or see a slight grey color. IF so, it's your backlight. Could be the fuse on the motherboard or the actual backlight in your display etc.

Next you want to connect an external monitor. If that displays properly you know the GPU on your motherboard is processing the graphics appropriately. If it does not you know the error is within the GPU circuitry on our motherboard. That will require you to have the schematic for your motherboard as well as equipment to do board level repairs.

If an external monitor displays everything properly, you could go ahead and measure the output on your display connector on the motherboard but we would need to know the make and model of your motherboard and see if there are any schematics for it out there. Or you could just try and replace the LCD. It's a bit of a gamble.

Download the maintenance and service manual for your computer from here Page 63 will show you how to replace the display.