I have my photograph files (CR2s and JPGs) as well as my Lightroom catalogue on an external USB flash drive.
For a reason too longwinded to post here, I needed to change the name of the external USB drive from "Photographs" to "Seagate." As soon as I did this, I realized that Lightroom could not find my photos. Foolishly, I tried to fix the problemm by reverting the external drive back to "Photographs."
Now Lightroom does not seem to know most of my photos exist, Usually if a folder is missing, there is a little question mark beside the folder name. In my case, the folder names are not even listed in Lightroom. It's like they don't exist. If I look at the external drive, I can see that all the photos etc are still there. How can I get Lightroom to recognize them?
Also, for the future, what is a better way to rename an external drive so Lightroom does not get confused?
"the folder names are not even listed in Lightroom"
Most likely is that you accidently started a new (empty) Catalog.
On the Lr top menu- choose FILE > OPEN RECENT... and look for other Catalogs, one of which might be your catalog with the 'missing' folders.
Or- use your OS file browser to find all .LRCAT Catalog files and open each to find the one with data.
Or- Restore a recent Backup Catalog from its zip folder that may have the data.
When you find your missing Catalog, then you can relink the folders in Lr (with a ? ) with the folders on the external drive (whatever its name!). Start at the very 'Topmost' folder shown in the folder panel.