When I launched Lightroom this morning, it indicated my catalog was being used by another application and asked me to choose a new catalog. I selected the one I thought was the most recent, and everything is gone except 81 photos I played around with on my 30-day trial. Please help!
Using your operating system, you need to find your regular catalog file (not this other one with 81 photos). In the folder that contains your regular catalog file is a file whose name ends with .lock. Delete this .lock file, do not delete anything else.
Then, launch this particular catalog file by double-clicking on it.
Thank God! It worked. Thank you so much for your help.