Looking for a way to contact wordpress,
If you're self hosted (as opposed to wordpress.com), there is no one to contact. Your site and server are your responsibility.
I've lost my password and the e-mail address I used must have been from one of the domain names I let expire
If you are self hosted, there are some documents that should help you reset your password and admin info: Resetting Your Password If you're trying to retrieve data from a domain you let expire, contact the support group at the hosting service where you had the site and see if they have any options for recovering those files and databases for you
I need to retrieve my password from that account and delete this one
The account you have here in the forum has nothing in common with any other wordpress login or password you might have elsewhere. There is no relationship between your wordpress site user information or administration, and this site.
If by chance you're concerns involve a free wordpress site that is, or has been, hosted on wordpress.com, you will need to contact support at http://en.support.wordpress.com/ to get those resolved.