Unity page gone in ver 40, 39, 39, 37 after graphics driver update

[Stephen Lewis]

Above should read 40, 39,38, 77. After installing a graphics driver update for Invidia, the unity page disappeared and login is only via terminal mode. Best I can find is a short msg which reads "pipe broken". I'm not unix savy so please bear with me. I tried uninstalling ver 40 and reinstalling it without success. Also tried recovery mode, which is where the previously mentioned msg appeared. So at present I'm using prev. version of Ubuntu 36, which is working fine. When I check for updates, it says I'm fully update. So my question simply is, how do I get the current version (40) back to showing the Unity screen upon booting. Thanks in advance for such a nubie question.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.11
ProcVersionSignature: Ubuntu 3.2.0-36.57-generic-pae 3.2.35
Uname: Linux 3.2.0-36-generic-pae i686
ApportVersion: 2.0.1-0ubuntu17.2
Architecture: i386
Date: Sun Apr 21 11:46:51 2013
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1366562086
 com.ubuntu.update-manager show-details true
 com.ubuntu.update-manager window-height 726
 com.ubuntu.update-manager window-width 600
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager
Symptom: ubuntu-release-upgrader-core
UpgradeStatus: No upgrade log present (probably fresh install)