Ubuntu – How to reinstall unity desktop on Ubuntu 14.04

Yes, if you need a classic menu in Unity you can use "classic menu indicator applet", press Ctrl+Alt+T on your keyboard to open Terminal.

When it opens run the commands below:

sudo apt-add-repository ppa:diesch/testing
sudo apt-get update
sudo apt-get install classicmenu-indicator

To run the classicmenu immediately hit the super key, type classic then click the classicmenu icon. A new icon will appear in the top right hand corner near the clock.

Else you can open application via the Unity dash

Links

1. https://askubuntu.com/a/46811/39372
2. What are PPAs and how do I use them?

If GUI is troubling you, login through CLI(Ctrl+Alt+F1)

Check if ppa-purge package is installed or not.

Run

dpkg -l | grep ppa-purge

If it returns the value, ppa-purge is installed. If not, install it as follows;

sudo apt-get install ppa-purge

After that run the following commands;

sudo ppa-purge ppa:gnome3-team/gnome3-next
sudo ppa-purge ppa:gnome3-team/gnome3-staging
sudo ppa-purge ppa:gnome3-team/gnome3

sudo apt-get remove gnome-shell ubuntu-gnome-desktop

Reboot system and login through Unity.