How to recover from a display driver problem

[Jim]

Ubuntu 14.04 with Nvida GeForce 9100 graphics with 2 monitors.

I was having problems displaying double underlines in LibreOffice and 
when nothing else worked I decided to try  a different driver. I had 
been running the Nvida proprietary driver. Like a dummy I did not write 
down it's version number, but I know the version I switched to was vers 
340.96. Numerically I remember the original drivers version was smaller. 
I tried to make the switch using the software updater's additional 
drivers tab.

When I rebooted the desktop appeared but the mouse moved very slow and 
then the desktop froze and then both monitors turned a pale blue and I 
had to use the power button to restart. I rebooted again with the same 
result.

I tried the advanced option from the grub menu.  In the recovery mode I 
  selected failsafeX. Got a message saying I was in low graphics mode 
but graphics settings could not be detected correctly and I would have 
to configure them myself. I then get a pop up saying Run in llow-grapics 
mode for one session, Reconfigure graphics, Trouble shoot the error or 
Exit to console login.

At first I could choose run in low graphics and it would boot to a 
desktop that was mostly covered by a list of resolution it tried but 
could not use, then the screen would go black.  After a few tries every 
option led to a black screen with a flashing cursor.

Anyone have any ideas of how to correct this without a complete reinstall?

Thanks, Jim