I inserted a new video card (Asus GT630-SL-2GD3-L). It was not initially detected by Ubuntu 13.04. I went ahead to the Ubuntu software center and downloaded the nvidia-current driver. Upon reboot, after the Ubuntu splash screen, all I got was a blank (black) screen. However, in experimenting, I noticed that the computer was operating normally except for the display. The video card, for some unknown reason, was eventfully recognized by Ubuntu and also correctly displayed the monitor information.
As an attempt to fix the blank screen, I reloaded the ubuntu-desktop, unity, and xrog. But none of these actions restored the display of the Launchpad and icons.
I found, on August 29, 2013, the solution at these websites. How To Reset Compiz And Unity In Ubuntu 12.10 Or 13.04. Also see: Reset Unity and Gnome to default values [duplicate]. Specifically the post by ZTA, which is the third post down. The launcher/icons were restored. Problem solved.
Since originally making this post, another link was made available that shows both the problem with a solution. "Unity doesn't load, no Launcher, no Dash appears". This post is worth reviewing too.