Dell 1525:LCD works only in MediaDirect mode

Hello,
I am using Dell Inspiron 1525. Windows Vista.
for past few days I am not getting anything on the laptop lcd screen. the backlight is there.

Surprisingly when i boot into MediaDirect mode the laptop screen works fine, i can see movies photos using media direct.

But when i try the normal boot, nothing appears on the screen.
Connecting to external monitor works fine.

Any solutions, how can i get the display back in normal boot. Not even getting the BIOS displayed on laptop lcd.

Googling it got a note about EDID settings but not very confident to modify them.

Please Help !
Many Thanks in advance