Mellon, it's already too late. There seems to be no way to get back to the kind of desktop I had before this whole mess went down, short of installing a 2011 version of software
and trying to update it without losing the desired performance. --doug
All of us, including you, started with a default desktop, then made whatever modifications we preferred. Whatever your desktop looked like before, you made it that way, so starting from the same original desktop, you can do it again.
There's no reason to reinstall your system, just start with the default desktop, and change one thing only. Taken one step at a time, you can eventually end up with the same, or even better desktop as you had before.
As for those telling you you can't copy the .kde4 desktop configuration directory from one installation to another, I have essentially the same desktop on all my many installations, because I have one original setup backed up to a data partition, and I just copy it to any new installation, then make any individual modifications I may want from there.
The worst that can happen if you copy the .kde4 directory from the other installation to this one is that you may not have a specific application installed, and the icon for that app won't be usable, or you may have an additional application installed and not have a desktop or panel icon for it yet. You then have the choice to install that application or delete that one icon, or add the icon if the latter case is involved. Either way, it's a rather simple process, if you don't panic and try to make too many changes all at once.
If you do copy the .kde4, and you don't have the same wallpaper on the second installation, as you had on the first, you'll also have to copy that wallpaper over too, than select it as your background, just as you did the first time you used it.
To illustrate, here are two screen shots of a VM, that has essentially the same desktop as the host machine. There are minor differences, because each has had modifications made since the original .kde4 was copied to each. There are differences in the launcher icon arrangement in the Panel Quicklauncher, and there are different applications running in the System Tray, and the color of the clock fonts is different. The icons on the desktop, and the desktop wallpaper are also different, but could easily be made the same, if I wished to do so.
With the VM reduced in size, to show both desktops.
With the VM maximized to show the similarity of the bottom Panels.
Both have the Smooth Tasks in the narrow upper Panel, and each upper Panel has a Dictionary and a single row Quicklauncher added, with different launchers in each.
In the Pagers, one can see that a number of apps are running on different desktops on the host, while only one app is currently running on desktop 20 in the guest VM.