The entries on the Site administration menu are generated in code. The problem you're seeing is more likely to be caused by an error in your plugin code rather than something missing from the database.
You should probably turn debugging on -- https://docs.moodle.org/23/en/Debugging#What_to_do_if_you_cannot_get_to_the_admin_screens -- to get a clearer idea of what is going on. If that still doesn't show anything, your web server's error log file will contain information to point you in the right direction.