database repair

I recently began using this plugin, but I have very little actual experience with it. What you might do is to first use it to make a backup, then see what effect its “Repair” button might have:
http://ww.wp.xz.cn/plugins/search.php?q=WP-DBManager

You can repair, analyze check, drop and … your database using Phpmyadmin too which is so easy to do. Its recommended to make a backup from your database before doing it.
The details information and guidelines can be found here: http://php.about.com/od/mysqladministration/qt/repair_mysql.htm