Comment 59 for bug 576648

Hey Don -
When your computer boots up, go ahead and make sure an Ethernet cable is plugged in. Then hold down control and alt and press "F1" - you'll be prompted to login with the user account you created. Then run this command exactly:
sudo apt-get install linux-headers-generic

It will prompt you for your password and such. I'm not sure that will completely fix it - you may also have to remove the nvidia driver from your system as well - if that's the case type the following:
sudo apt-get remove nvidia-
BUT DO NOT HIT ENTER.

Hit tab twice - it should show you the available packages to remove... something along the lines of nvidia-313-updates
Go ahead and complete the line with whatever is shown ( ignore the packages with settings and common in the name ).

Reboot and you should have you desktop back. Once you've done that you should be able to install the nvidia driver again and it should be fine - I suggest the 313 package as that is the one I've gotten to work.