My laptop screen backlight is off

Hello,
I have an asus i5 windows 7 64bit laptop with a radeon hd 6370m 1gb graphics card
I was using it for a while until i noticed that the graphics card is detected as standard vga so i went ahead and downloaded it s catalyst which i believed was needed at the moment
After rebooted the pc everything looked fine untill it reached the windows loading screen where it immediately went dark or very dim
I believe it s the backlight since i used an external screen and it worked perfectly
I hope someone can help me because i was planning on still using this machine