Did you try to set default appearance settings. If not go to Configure
Desktop->Appearance->Colors, and uder Sheme tab, select the Default
Scheme and hit apply
Assuming you are in Kde4, try opening Personal Settings and then go to
Appearance/colors/, hit the dropdown and choose Window, then change the
setting for alternate background.
There are other items in that dropdown and you most likely can change
the text color as well.