If you run your system as a normal user, you can't mess up anything of your system except your own personal /home/... directory. all settings are stored inside that directory too.
that's a good thing to know. (therefore don't run as root, because you can mess up everything!) Every user account doesn't interfere with the settings on another one.
The KDE taskbar is called "kicker", but I'm confused why it doesn't restore. Perhaps it is still running, because the "X-kill" only terminates the connection to the display (and an application should close itself)
* Open a console window. (for example, Alt+F2, type "konsole")
* Check if the kicker is still running: type ps auxf | grep kicker
. It wil select kicker from your running processes.
* Type kill <process id>
to kill the program. The process id is the second field in the kicker line that just appeared at your screen.
* Press the up-arrow and 'return' again to execute the command for a second time; just to check if it's really been killed. It's killed if you see "No such process" at the screen.
* If the program didn't respond to the terminate-signal, you can ask the kernel to remove the program: kill -9 <process id>
* Type "kicker" to start your KDE taskbar.