"Is there any way to solve this problem?"
You can rename the /home/user/.kde to something else (say /home/user/grasshopper). Then the next time that you log in as user KDE will act like it did on the first login after you installed. You will have to reconfigure KDE. You can save some time by copying some of your old setting in /home/user/grasshopper to your new /home/user/.kde but be careful because some of the information in /home/user/grasshopper is obviously corrupt.
Creating a new user also will work but it is probably easier to do it by renaming /home/user/.kde
Be prepared. Create a LifeBoat CD.