my laptop hp pavilion 9000 doesn't display although the machine looks working and it can be displayed by external source like projector and other monitors,the connection between motherboard and hp display is intact and display drive works normally.what could be the cause of not displaying?the screen is black.
Shine a light on the screen. If you can make a a faint image the backlight may have failed or the inverter may have failed. Since an external monitor works the graphics orocessing unit is still working. How old is the laptop?