Lightroom crashed after I exported pictures. I had to shutdown the computer. When I turned it back on and opened Lightroom, my pictures were gone. I have tried to find a backup file and I can't. I have gone through all of the online options I could find, and nothing has worked. Any ideas would be appreciated.
Lightroom is a non-destructive photo editor (see Are RAW files safe from changes?). It means that it never touches your original files (unless you ask it too). So regardless of Lightroom state (the software itself or its catalog), you will find your original images where you put them (or where you told Lightroom to import them).
Concerning your editions, they are indeed in the LR catalog and could possibly be stored in sidecar files (see Where does Lightroom keep changes? and Why employ the xmp sidecar file in Lightroom?). If your catalog has been corrupted, you should be able to retrieve a backup copy. To know where your catalog and its backups are, in LR go to Edit > Catalog Settings.
As a last option, you can also try to re-import images using LR and selecting your hard drives but it may discard your edits. It may help to locate the images you are looking for. You can also try to search for them in a files explorer.
This answer is valid only if your images are locally stored (no online hosting service involved).