Did everyone's "recent unread posts" and "unread since last visit" links disappear, or just mine? I'm still logged in and everything else seems normal, but now I can't quickly check to see what's new.
At the far right of the bar at the top that says "Hello anisogamy," after the date and time, there should be an icon that is either a little plus or a little minus. If it is a plus, that means you can click on it to expand that top header to show the "unread posts" and "new replies" links. You may accidentally have clicked on that button and closed it without realizing.