BigGuy, Welcome to LR Forums. Sorry you've lost the images.
If you've used non-LR external search tools to look for your image files, and can't find them, then it's likely they're gone. If by some chance you do locate the missing original files, we can help you get them reconnected to the LR catalog.
While it's possible, it's not likely that LR deleted the files without your knowledge, because:
a) it takes forever, (see complaints about slow deletes)
b) it very, very clearly asks whether you want to delete the original files or just remove them from the catalog.
As you've discovered, in order to export images from the catalog, the original files need to exist, and be locatable by the catalog.
However, there is one last gasp possiblity. The LR database maintains a cache of rendered images in order to accelerate on-screen image navigation. It's possible to extract those cached images; their quality will of course depend on what settings you applied to the image rendering process. Marc Rochkind's LRViewer is a 3rd party software that can save out the rendered previews as image files. Look here:
http://basepath.com/ImageIngester/
For future reference, once images have been imported into LR, it's usually always best to do any file moving, renaming, folder maintenance, etc, from within LR. If you mamipulate files externally to LR, with Finder/Explorer or other OS tools, there's just no way for LR to keep track of the changes.
I'm sure your images have great value to you. You may want to consider some sort of backup strategy to keep them secure. These forums, and other LR sites have a great deal of info on various 'best practices'. Another good reference is Peter Krogh's "The DAM Book", a handbook of Digital Asset Management. Google his website.
