LrC no longer has my picture folders

That's a classic sign that you have opened a different catalog than the one you expected. 

Do you know where your catalogs are stored? In the LrC File menu, choose Open Recent. There you should see the names of any other catalogs you have used.

If you have just upgraded from one version of LrC (for example V1.2x to V13) LrC might have created a new catalog for you if you didn't follow the instructions exactly when V13 opened for the first time. 

When I went in today though there are no longer links to my folders where my pictures are stored. 

By @jos78186553

What does this mean? Does the folder name appear in the Folder Panel? Is there a question mark icon next to the folder name? Or is the folder absent and does not appear in the Folder Panel?

I think it wants me to import the photos again.  I have fussed with it for quite a while but haven't been able to find them.  And I can't use my pictures directly from my computer because they're dng files.  I'm at a loss on where to look or how to deal with it. 

Importing the photos again is almost always the wrong thing to do. Once we know the answers to the questions I asked earlier, we can advise further. DO NOT IMPORT THE PHOTOS AGAIN.

Was this an upgrade of LrC, and as a result an upgrade of the catalog?