When we register a username account the matching blog is reserved for our future use. It cannot be obtained by anyone other than the person who has registered the matching username. I have flagged this thread for Staff attention so you can register the reserved blog.
In order to help you get access to your blog Staff need one of the following things in order to correctly identify you as the blog owner. (1) the email address (2) the wordpress.com API key for your account (it was included in your welcome email with a note to keep it safe). There must be a limited number or possible email addresses you could have used and it’s the email address that is the unique identifier.