I installed KDE (kde-plasma-workspace) in Ubuntu 11.10. After some configuration it became buggy. How can I revert to its default settings?
Log out of KDE by pressing "CTRL" + "ALT" + "F1" to exit the window manager and bring up a command line. Kill any remaining KDE processes by typing "ps -ax" and looking for processes marked "Xorg," "KDE," or "KDM." For each one of these processes, type "kill -9 " where is the number under the "PID" column in the output of the ps command. Enter your home directory by typing "cd ~".
Back up the KDE directory and delete the original. Type "mv .kde .kde.old". This moves the entire contents of the .kde directory into a new directory called .kde.old. (You can call this directory whatever you want.) The original .kde directory is removed.
Restart KDE by typing "startx". You will be asked a few configuration questions, as if you were running KDE for the first time. After that, KDE will load with a fresh configuration.