And I don't know how. An entire directory seems to have just vanished, and I only found out when I tried to use one of the files in it.
So I went to my latest backup. It wasn't there either. Because the latest backup was a backup of the computer without that directory. Huh.
So I went to the backup done 4 days ago. And there it was, so I copied it back to where it should have been. Panic over.
I actually have three sets of backups; one is done on the 1st to the 10th of the month, one on the 11th to the 20th and one on the 21st to the end of the month. The reason for this is exactly the scenrio that just happened.