It sounds like you're trying to upgrade an installation that has already been partially upgraded but failed in progress. If you don't have a clean backup, you're going to have to work through the upgrade file (dbscripts/xml/upgrade.xml) to find out how far you got and complete the task by hand.
If you got as far as the error message stating that the rt_settings table was missing, it means you may have to run the commands in upgrade/2.2.0_update.xml manually; once you've done that, try inserting the new version information into the versions table and setting it to current. (If you need help with that, let me know and I can provide more detailed instructions.)
If you have any information on the original upgrade failure, please let me know -- and please back up before trying any administration tasks like upgrades!
Open Journal Systems Team
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