naked desktop

I installed and ran the Avast 4 free home version and then ran a free registry cleaner that I found online. The next day I found that not only are all of my desktop shortcuts missing (no icons showing at all) but also my Start button and everything else along the bottom of the screen is gone! To start up my browser or any other program I have to use the keyboard to bring up the Task Manager. I have to do the same in order to shut down the system. Now I can’t access my Control Panel or my Recycle Bin. What happened? Is there anything I can do to fix this? I tried using the F8 key at start-up to go back to the last known good configuration and that didn’t change anything. Should I do a non-destructive F10 or what?

It would have been nice if you had mentioned which registry cleaner?
Not to mention what OS you are using?
Playing with the registry can seriously damage your system, be it using a registry cleaner or manually.

Without knowing what you did within the registry cleaner, it is hard to say what to do, but most registry cleaners worth their salt should have an option (usually a default action) to backup/copy stuff that it/you elect to delete.
If so you should have been able to restore that set of deletions and hopefully that should have restored things.

Now that you have used Last Known Good Configuration (LKGC) I don’t know if the action above will work. You should really have sought help before trying system restore/LKGC.

I have no idea what you mean by ‘Should I do a non-destructive F10’?

Did you try your friend google? I did and it returns lots of hits for ‘restore start button and task bar’ without the quotes, hopefully there is something there.
http://www.google.co.uk/search?q=restore+start+button+and+task+bar