How to fix my hp pavilion 5000 series laptop

Hello,

Hello,
i don't know how to fix my hp pavilion 5000 series laptop
the laptop is working, have the necessary sounds after i
turn it on, but the problem is that the screen stays always black,
..i connect the lap top to tv screen there is no display, it shows nothing or it isn't working properly, even i changed the screen with new one
..so i just have no idea why my screen is black, why can I fix it ?