In the interest of full disclosure, I also modified the dimensions of the header graphic in the css.

Honest, that's all I did.  =0)

What do you mean you cannot access the plugins enable/disable panel? Is the Tools Administration link missing?

When I navigate to the Settings page and click on "Configure your Tools" (which should be Configure your Plugins) it refreshes the page and does not show the plugins as it used to.

I use 'Adminitration', 'Tools administration' to get to the plugins 'enable/disable' panel with my theme sailboatskipper. 

Thanks Clyde.  Same here, except it doesn't work for me like it used to.  

Settings->Configure your Tools  is for users to configure options. Very few plugins add settings to this page so it is usually empty. The only one distributed with Elgg that does this is the twitter service plugin. 

To enable/disable plugins, go to Administration -> Tools Administration as Clyde points out.

When I log in as the administrator, there is no Administration, ergo no Tools Administration

Am I hopelessly hosed?

Sounds like the 'Adminstration' link has been hidden or removed by the changes you made sailboatskipper.  Maybe replacing the original files (or deleting any 'theme' file you are using) would make it appear again.

screenshot at:  www.idellc.com/temp/screenshot.png

Yes sailboatskipper...but 'Adminitration' should be one of the index links you see as soon as you log in (as admin).  Is it there on any page?