Everythings gone a touch dark...

[Guest]

Hi, linux beginner here. I installed Kubuntu via WUBI thinking as a novice this would be a good idea. At first it was brilliant. Unfortunatly like a nutter i was adjusting screen saver settings and the whole screen has now gone black.

I log in as normal and i see the desktop load then everything goes black, i can still see the mouse and move it.

Is there any shortcut keys i could use to reverse what i did or any advice?

thanks