One sure-fire way to reset your KDE settings is to remove the .kde directory in your HOME directory. However, this will also wipe out a lot of data files for your KDE apps. This includes things like all your rules and mail account details in kontact/kmail, your kontact address list, your kalendar dates etc.
I have been in a situation like yours in the past. What I did was to close down KDE and log in with a different window manager. Then I re-named the .kde directory to .kde.old
Then I logged back into KDE and saw that I had default settings. After that I had a bit of a battle trying to identify and copy across settings from the .kde.old folder manually. I think that in the case of my kontact/kmail email rules I just set them up again (which was a pain). The kontact names were OK as I had a backup in that electronic business card format elsewhere, which I just imported.
Having said all of that, it might just be that the systray-like app is not running. I think it is called "kicker" - try running it by pressing alt-F2 and entering "kicker".