Ted,
Since it sounds like you have access to PHP MyAdmin, please run the following SQL query:
UPDATE `XYZ_extensions` SET `enabled` = 1, `access`=1 WHERE `name` = 'plg_authentication_joomla' OR `name` = 'plg_user_joomla';
Please make sure you replace XYZ with your database prefix.
Alternatively, look to see if the authentication and/or user plugins have the 'enabled' field set to '0'. If so, fix that manually. That would be why you can't login. The above SQL will also reset the Access column to '1', making it public, which is required for them to function as well.
Definitely let us know how that goes. JFBConnect doesn't change the Joomla User or Authentication plugins at all, but sometimes mis-clicks that disable them can lock you out of your site, as you've see.
Good luck,
Alex