Using 'tasksel' , aptitude failed (100). So, I instead entered 'sudo apt-get install ubuntu-desktop'. This resulted in the following message:
Some packages could not be installed. This may mean that you have requested an impossible situation or your are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
ubuntu-desktop : Depends: unity but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
If you have any ideas, I would appreciate them. I will keep researching and post any success I have.