accidentally removed my taskbar. how do I reactivate it to be displayed again.

I just migrated from windows to kubuntu 9.10 and I'm learning on the fly

Just right-click on your desktop and use add panel.
Then you have to add all the stuff you need like the menu, the desktop switcher, maybe a clock, the stuff where opened windows are displayed and the area where the icons are displayed...

I hope you know what I mean. I don't know the english names... Sorry about that.

Here's a list of Screencasts explaining how many things in plasma works.
http://userbase.kde.org/Plasma/FAQ/HowTo

I just need to re-activate the task bar as it was after I installed the kubuntu

There's no re-activating something you've deleted as it was just a setting. But deleting the files related to plasma settings would create the original state after installing - but that would also include the desktop. Try deleting all files with plasma in it in ~/.kde/config/

Good look

already solved the problem, thank you very much for your help:D