ubuntu side bar missing solution

to get command line interface to run this press "CTRL+ALT+F1" 

now login using your username and password to run the following commands:- 

first try this 

initctl restart unity-panel-service 

else try this 

sudo apt-get update

sudo apt-get install --reinstall ubuntu-desktop
sudo apt-get install unity
sudo shutdown -r now

mv ~/.config ~/.config-bak