Old Admin is Gone

Hi,
I run a blog for a non-profit and it seems the username we had on file is not the full site admin (mptvfundblog.org). On top of that, the last admin apparently installed disqus which is a big problem for two reasons:
1. We can’t get disqus to load on the page, and therefore can’t see comments.
2. Disqus is forcing people to log-in to comment, which is not something we do. We prefer to moderate comments.

I found the disqus page where the comments are landing and was able to reset the password, but I can’t disable loggin in via disqus (what a horrible program).

I also can’t access any of my site’s settings as we don’t even know the old username of the person who apparently has full admin access.

So now what do we do? Definitely need help here ASAP as we just announced a new partnership and expect people to have things to say. I was able to log-in and post the announcement, but now I’m handcuffed.

So how do I: A) get admin access, or barring that B) at least find out who the admin is on the account so I can try for a password reset.

Thank you for your help!