Yes, if you lock yourself out of Discourse when configuring SSO, go to http://forum.example.com/u/admin-login. (Replace forum.example.com with your forum’s domain.) Enter your email address into the form on the page and click the link in the email that you are sent.
Once you have logged back into the site, check to see if a new account was created for him. To get logged into an existing account on Discourse, you’ll need to be using the same email address on WordPress as you do for the Discourse account.
Have a look at Debugging and fixing common SSO issues to see if it gives you any clues for solving your SSO problems. The issues you are having are probably related to what’s described in the ‘Solving require_activation SSO login issues’ section of that topic. I don’t think your site is using the default WordPress registration system, so new accounts that have been created since you installed the WP Discourse plugin will have the require_activation flag set to true in the SSO payload.