'root' locked out of KDE :-(

Hi! I've upgraded from 8.0 to 8.1 All went fine. I've update YOU and then udpate the rest All went fine. I've created one user'laotoma', apart from 'root'. No problem to login under KDE as 'laotoma' or 'root' I started playing with the system, and now, under KDE, I can't login as 'root' anymore, nor is the CORRECT password for 'root' accepted when I try to run YAST2 as 'laotoma'. I guess it might be because I set the system as 'paranoid'. I played also with the Video Card settings and I need to change them. Question: how can I login again as 'root' under KDE and then run YAST2? TIA Lao Toma