Earlier I posted about my screen saver not allowing me to connect to my Aperture libraries. Now I know why - I seem to have lost everything. (the pictures are safe - they're backed up in a referenced file.)
I was working in it last night, making edits to shoot I did over the weekend. This evening I opened Aperture, got some weird error about re-connecting files, said OK, now I have 1 project with only 19 photos (that's down about 20,000). All my files are gone, my pre-sets are gone, my vaults are gone.
Looks like I have to re-connect to everything, but I don't have any idea where to start.
Never mind, I figured it out.
Somehow I opened a very old library. I was able to switch back to my working library very easily.
I guess I need to go do some research on how to use libraries.