@stephenopoku when you changed the LCD display, you made sure that the new one is a good, working one and is the exact same model? Turn the computer on and make sure that it starts up. In a darkened room, use a flashlight and shine the beam at an angle against the screen. See if you can make out shadows or shapes. If you do, then it is your backlight that has failed. Since this is a new display, it would be either the backlight driver or the backlight fuse as well as the display connector. We would need to see your connector as well as your motherboard. At least we would need to know what make and model your motherboard is.