laptop boots up but has a black screen

[mastXploder]

Trying to help my friend troubleshoot his laptop. It turns on just like it normally would but the screen remains black. Did the usual of hooking it up to an external monitor and oddly enough it displayed video, and video also was restored to the laptop display. After unhooking and rebooting we were back to the original problem with the black screen. Just wondering where to go from here or if anybody has any tips or advice on how to fix this. His laptop is a Toshiba Satellite M3050-S4831

 

[itsVance]

Should be able to use the function key to switch the display back to the laptop. Might be fn and one of the F keys. The F key would have a picture indicating its function.