What script or scripts control the appearance of KDE4?

How can I get them to their default conditions?

Yesterday I upgraded - on line - from Kubuntu 8.04 to 8.10
and it seemed to work pretty well, all the old apps and data
intact. Then, in the process of adjusting the screen's
appearance, I managed to achieve an absolutely blank white
screen, populated only a very worried-looking cursor. No
bars, buttons, bangles - nada. As a guess, all colors,
foreground, backgound, whatever, were set to white.

I can reboot to the command line, of course, but as a newbie
I'm not sure whether to start with ~/.kde or with /etc. All
I need at the moment is a way of reverting to plain-vanilla
KDE4, from the command line.