I am new to linux. I have ubuntu desktop version installed on my PC and it's the only OS on the machine. I has been working fine. Since I recently updated all the software packages everything on my desktop disappears. I can call up the right-click menu, and create files and folders via it. I can turn on and off the computer by pressing the power button. The OS is reacting to my action but the task bar and menu on top and bottom are gone.
Has anybody seen this? Is there anything I can do to roll the system to back to the previous normal state? P.S. I can use command line.