I was deleting spam comments, and — due to slip on the touchpad — deleted some real ones as well. I’ve checked, and there’s no way to bring them back. That’s one of the annoyances about the Movable Type software we use on this blog, but later for that. Right now I apologize. This was my fault, and valuable comments disappeared.
I can restore them in another way, though. I get email notifications of every comment that appears, with the full comment text. I’ll take the vanished ones, and either make them a new blog post, or (a better idea) new comments, with the text of vanished comments reappearing as comments on the post they were originally made to.
I’m so sorry about this. But later on today I’ll do one of the fixes I just mentioned.