When I arrived at the office I noticed that the taskbar is missing in my KDE4 Fedora workstation. Good thing is that I have a KDE konsole application still left running. I didn’t realize early that the solution to revive the taskbar was that easy.
First thing I do was to launch Firefox from terminal then searched for possible solution. The solution was just to run this on terminal.
plasma-desktop
That’s it! XFCE has same weird problem as well and you just have to run similar application (different name though) to bring back the taskbar or panel.