Did you set the pref to 0?

See Restore the default Smart Bookmarks Folders

Yes, I have tried that. It always resets back to 2

Setting the pref browser.places.smartBookmarksVersion to 0 should trigger the creation of those special folder. Firefox sets the pref to the correct value after that has been done, otherwise you would end of with a lot of such bookmarks as each Firefox start would create an extra set. Did you look in the Bookmarks Toolbar folder?

You can also try: http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox http://kb.mozillazine.org/Bookmarks_not_saved

I've checked, and the folders still aren't there (either in the main bookmarks, or in my bookmarks toolbar folder). I've read through the links, and I'm not sure if they're applicable. I just imported a JSON file to get to where I am, so I don't think erasing and re-importing it will do any good.

You can create new bookmarks to restore those smart folders.

Most Visited: place:sort=8&maxResults=10 Recently Bookmarked: place:folder=BOOKMARKS_MENU&folder=UNFILED_BOOKMARKS&folder=TOOLBAR&sort=12&excludeQueries=1&excludeItemIfParentHasAnnotation=livemark%2FfeedURI&maxResults=10&queryType=1 Recent Tags : place:sort=14&type=6&maxResults=10

How do I create those bookmarks? I found similar advice on other websites. Firefox doesn't seem to recognize the 'place' address (unless I'm setting it up incorrectly when I make a dummy bookmark and change it's properties to match the above 'place' links).

You need to close and restart Firefox after you have created a bookmarks with a place: location. That should make it work like a smart bookmark.

See also http://developer.mozilla.org/en/Places_query_URIs