Ubuntu 14.04 Black Screen

[yaboiduke]

I have an HP255 G1 Notebook running Ubuntu 14.04. It had been running over night but when I opened it, the screen was black. Its booting up fine and displaying to a second monitor. The led backlight looks to be working fine as it is responding to keypress or F4 display changes but it is not displaying anything. I suspect it may be the graphics drivers but have no idea how to reinstall them. The system settings tell me its runnin Gallium 0.4 on AMD Kabini. Help?

 

[popatim]

Moved to laptop tech support.
Its not the drivers otherwise you would not get external display either.