Excerpts are gone upon upgrade

Upon upgrading to 3.2.1, excerpts vanished. I googled the problem and found that as of 3.1 excerpts are hidden by default and all you need to do is go to All Posts : Settings and check the “Excerpts” box. Except…there is not such box. My problem is without excerpts my RSS feed shows up with only a title and a “read more” link with no excerpt, no description and no post. What to do?