April 18, 2014, 11:24 AM — Ubuntu 14.04 comes with a new lock screen, but here's how to go back to the old one (Light DM) if you don't like it.
1. Open the terminal, type in this command, then hit Enter:
sudo apt-get install compizconfig-settings-manager
2. Go to the Unity Dash, type in CC to open the CompizConfig Settings Manager.
3. Go to the General Tab.
4. Choose Light DM from the drop down menu.
If you want to get the old Ubuntu lock screen back, you have to install the compizconfig-settings-manager, like this:
Image credit: Linux G