Please help me reset or reinstall Unity. I've already tried everything here as well as apt-get update and upgrade. My system entered this state after I re-installed the OS (12.04) in the hopes of curing its instability.
The curious thing is that Unity works if I go through recovery mode followed by resume.
Try this. Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the commands below.
sudo apt-get purge unity && sudo apt-get install unity
Reboot your system.
If the above does't help, try
sudo apt-get install --reinstall ubuntu-mono ubuntu-minimal ubuntu-desktop unity unity-common unity-2d
The problem was the simultaneous use of three video outputs (HDMI, VGA, and DVI) when only two can work at a time. I simply removed one of them and it booted right back up. Now that it is working I can re-attach all three and choose which two I want from the display settings.
