Having a Blank screen. Backlight/inverter/GPU or other problem?

Hi all,
My lap-> Acer travelmate 4730G.

When I was playing nfshp2 game, display dimmed for two times.
When I restart -> the resolution was low (1024*768). The screen is in left side. Not centered. I couldn't abled to change resolution. I used like that for a day (sometimes display had a blank screen).

In those times, it had another problem. When I change the brightness, it won't change it step by step. Instead when I press Fn + right or Fn + left, it change the brghtness to top most and after pressing again it come to the lowest brightness.

Now its totally blank. I can see display content with a flash light. The resolution is 1024 * 768. Also not centered, its in left side.
It work perfectly with an external monitors (I can change the resolution).

What is wrong. If it a Backlight / inverter problem, why I can't change the resolution of internal display?

Please help me.
Thank you