How can I get out of low graphics mode on 12.04? [duplicate]

I have recently received a similar issue with my System 76 Pangolin Performance laptop. The folks at System 76 told me to run the following commands:

sudo chown lightdm:lightdm -R /var/lib/lightdm
sudo chown avahi-autoipd:avahi-autoipd -R /var/lib/avahi-autoipd
sudo chown colord:colord -R /var/lib/colord

These commands did the trick for me.

While I believe these commands/users might specific to System 76 it's worth checking the ownership of the directories (if they exist). Also it would be useful if you edit your post to provide the company that makes your laptop and graphics card as a reference if this does not solve your problem.

Click your name in the upper left hand corner, select "Switch User Account...", when logged out click on the little ubuntu symbol, and then select Unity 2D, and log back in.

Do you have any idea what graphics card / hardware you're using? (Nvidia, ATI, or other)

I solved a similar problem by disabling the proprietary Nvidia driver. When you reach the login screen click the small circle with the ubuntu three friend logo to select a "unity 2D" session to login. from there use dash (super / windows key) to search for "driver". it's under "system settings > Additional drivers" . Then deactivate the driver in use.

If you installed and removed lightdm-kde-greeter and you want to go back to Unity try:

sudo dpkg-reconfigure unity-greeter
sudo dpkg-reconfigure lightdm

and select lightdm and reboot.

I faced this problem because there was no space left on my root partition

To check disk utilisation,

df -h