The boot-up splash and login screen may be changed while trying out different desktop environments in Ubuntu, such as KDE, XFCE, LXDE. This quick tutorial is going to show you how to restore plymouth splash and LightDM login greeter to default if you messed them up.
Restore plymouth the splash screen to default:
Launch a terminal window from the dash or press Ctrl+Alt+T. Copy and paste this command into terminal and hit enter, it will display a list of installed plymouth themes. The Ubuntu default is “/lib/plymouth/themes/ubuntu-logo/ubuntu-logo.plymouth”, choose it.
sudo update-alternatives --config default.plymouth
After that, run this command to apply change:
sudo update-initramfs -u
Restore Lightdm login screen greeter to default:
If your login screen has been changed, first run this command to choose LightDM as the display manager:
sudo dpkg-reconfigure lightdm
If not work, edit /etc/lightdm/lightdm.conf file with your favorite editor:
gksudo gedit /etc/lightdm/lightdm.conf
Make sure the greeter-session is the unity-greeter, then restart.