In Feburary 2016 21,
Click on 'Applications' in the top left corner of your desktop. A drop-down menu appears.
Scroll down and hover your mouse over 'Accessories.' Click on 'Terminal.' The Ubuntu terminal appears. The terminal is an application that allows you to enter command-line text to perform operating system functions.
Input 'sudo dpkg-reconfigure -phigh -a' into the terminal and press 'Enter.' Allow the command to process and the system to reinstall the Ubuntu distribution package.
In Feburary 2016 21,