Blinking underscore after NVIDIA graphics propreitary driver use/install on UBUNTU

I think I figured it out.

First, I had to use my Ubuntu installation CD, and chose "Try Ubuntu".

Next I logged into a terminal session, and have to remount my system partition (ie: /dev/sda1 is where I installed Ubuntu).

sudo mount /dev/sda1     /mnt
sudo mount --bind /dev  /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys  /mnt/sys
sudo chroot /mnt

This mounts everything I need to run apt-get against my hard drive, rather than the non-persistent Ubuntu running in RAM.

Now I just have to clobber Nvidia drivers, so I can get my system booting again.

# Remove existing drivers
sudo apt-get remove nvidia*
sudo apt-get purge nvidia*
# Housekeeping
sudo apt-get clean
sudo apt-get autoclean
# Handle any errors to due incomplete apt-get operations
sudo dpkg --configure -a
sudo apt-get update
sudo apt-get upgrade
# Remove xorg/X11/XFree86 references to graphics drivers
sudo rm /etc/X11/xorg.conf
sudo apt-get install ubuntu-desktop
# Clean up and unmount everything
exit
sudo umount /mnt/sys
sudo umount /mnt/proc
sudo umount /mnt/dev
sudo umount /mnt
exit

Now, I will NOT re-install the drivers just yet. Reboot the system, and eject the liveCD. I am now able to log into my existing Ubuntu installation.

Now, go into Jockey (ie: The "Additional Drivers" program, also /usr/bin/jockey-gtk), and see if any Nvidia drivers are "Active". De-activate them with the "De-activate" button, and reboot. Check if any new nvidia driver has been automatically activated. If so, de-activate it, and reboot again. Repeat until jockey no longer automatically activates any nvidia drivers at all.

Now, install the nvidia drivers we want:

sudo apt-get install nvidia-current
sudo apt-get install nvidia-common
sudo apt-get install nvidia-304

Now reboot the system. When you start jockey next, it should default to nvidia-304, and you're set.

I ran the command sudo xrandr -q and got the output:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1920x1080     60.02*+  47.99  
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)

Then the command xrandr --listproviders

Providers: number : 2
Provider 0: id: 0x1e2 cap: 0x1, Source Output crtcs: 4 outputs: 4 associated providers: 0 name:NVIDIA-0
Provider 1: id: 0x46 cap: 0x2, Sink Output crtcs: 3 outputs: 4 associated providers: 0 name:modesetting

Then the command xrandr --setprovideroutputsource 1 0 and then xrandr --current

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1920x1080     60.02*+  47.99  
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-1-1 connected
   2560x1440     59.95 +
   1280x720      59.86  
HDMI-1-1 disconnected
DP-1-2 disconnected
HDMI-1-2 disconnected

Notice DP-1-1 is now showing as connected. At this point I was able to open the display settings and see the Thunderbolt display. There I could enable it and configure. It appears to be working correctly now. I determined these steps from a post here

I then added the following command in the 'Startup Applications' dialog so that the settings persist after loging in and out.

/bin/bash -c "sleep 10&&xrandr --setprovideroutputsource 1 0 && xrandr --output DP-1-1 --auto --primary --left-of DP-0"