Your iPhoto Library may need repairing or rebuilding.
- Back up your iPhoto library as a precaution.
- Depress both the keys "option/alt⌥" and "command⌘" firmly at the same time and hold them down, while you launch iPhoto by double clicking the iPhoto icon. Select "Repair database" from the panel to repair your iPhoto library. If that does not bring the faces back, try also rebuilding the library.
LeonieDF - thanks for the suggestion. I did the rebuild of the database after it happened the first time and it seemed to get everything back in order for a few days and then it just happened again. This time it left 2 faces on the cork board (I had identified about twenty) and only a couple pictures in each face folder (there were about 3000 in each previously). I don't want to rebuild the DB again until I figure out why it's doing this so I don't keep spending hours identifying faces that are going to disappear again. Any other ideas?
Since repairing the library brings the faces back, you must be using iPhoto in a way that is corrupting the library. This can happen, when you are force quitting iPhoto and it cannot complete its database transactions, when iPhoto crashes,, because of corrupted images that you imported, when you keep the library on an external drive that goes suddenly offline, or similar reasons. What exactly did you do, shortly before the faces disappeared? Did you have crashes?
Is your iPhoto library on an internal or external volume?
Perhaps I didn't explain the fix correctly in my response. While everything seemed to get back working properly, the repair did not actually bring back the faces and identification that I had already done the first time around. I was able to start over and identify all the faces again --- that's what seemed to work for a couple days until it happened again. I was not doing anything differently than normal use and iPhoto didn't crash, I just closed it down and when opened it up again, the faces were gone. I am using an internal drive. ( I do have everything backed up on an external drive but it's not what I use on a daily basis and has not been connected during these issues. I appreciate the responses.