When I restarted my Ubuntu workstation after a firefox crash, my taskbar disappeared. I'm referring to the bar at the bottom of the screen, where the currently-open programs are displayed. Also, I remember I could switch from one virtual screen to the next one there. At the very right, there was a button on it that would minimize all windows and show the desktop.
What program do I need to start to get it back? What could be the reason for this?