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First of all 2.2RC is not for a production site.
If you need to go back, you need to have made a backup of your old site, then just restore your old site, (overwrite the new files with your old files, then restore your database.) . If not, you just learned the importance of backing up your site. Or you could just use the version you have , but learn about how it works, go into the admin area and look around, get to know how it works, if you look for the forum post about "2.1 debug" you can see some of how it works and things you need to do. Hope you get it worked out.
John