Question: 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?

Answer: 
Its Easy, hold `Super+Alt+click` on the upper task bar and click add new panel. Then using the same key combinations select `add to panel` and then select the options you want such a workspace switcher, etc
I reached this in search of an answer and found a solution myself. Maybe it will help the others. In the meanwhile 16.04, there is a possible to do this using tweak-tools. 

```
sudo apt-get install gnome-tweak-tool
sudo apt-get install unity-tweak-tool

```

Go to Extensions and activate : `Display a window list at the bottom of the screen`. Please see the screenshot ( 3rd point from below ) 

[![enter image description here](https://i.stack.imgur.com/W420f.jpg)](https://i.stack.imgur.com/W420f.jpg)