Connect an external monitor to the laptop and check if its’ display is OK.
If there is no display showing on it either, then you either have a GPU problem or a motherboard problem.
If there is a display showing on the external monitor then you either have a video cable problem, video cable connection problem (at either end - display or motherboard, a display panel problem or perhaps a lid switch problem.
To test if perhaps the lid switch is the problem try shining a torch at an angle close to the laptop screen to check if you can detect an image at all. It will be very faint so try this in a darkened room.
If you cannot detect an image then see the above.
If you can detect an image then you have a backlight problem. The lid switch controls the backlight power to the display panel. It is usually a magnetically operated switch with the magnet in the lid, below the screen and the switch in the case of the laptop, above the keyboard and the back of the laptop