I upgraded my blog software yesterday, and accidentally deleted the .htaccess file for this blog. That meant that, although the front page was working fine, the archive pages and RSS feed were broken. Thanks to Sheila for pointing it out to me.
Anyway, it looks to me as if everything is working again now. Please let me know if it isn’t. (Yes, I know that wouldn’t be any use if the whole blog were broken. But I think most of it works, so you might be able to read this but still find something broken.)