How do I get publicize to work again?
1. Try flushing your FB cache but disconnect from FB first http://umairj.com/146/how-to-clear-facebook-shares-cache/
2. Try the full reconnect procedure again detailed at http://en.support.wordpress.com/publicize/#reconnecting-facebook including step 3 (removing the FB app), which is probably the most important step.
3. See also publicize troubleshooting http://en.support.wordpress.com/publicize/#troubleshooting
Note: RSS Grafitti http://www.facebook.com/RSS.Graffiti can be used for posting to Facebook walls if you prefer. RSS Graffiti periodically checks the RSS/Atom feeds that you specify and posts any new entries it finds to the Facebook Walls that you specify. You can get any feed written on any wall (Facebook Profiles, Fan Pages, Groups, Events and Application Profile Pages). In fact, multiple feeds to multiple walls. You choose the combination.
How do I publicize the posts which have already been missed?
You will have to post the titles and links manually.