With anonymous ownership comes responsibility. You have to maintain access to your blog, without requiring additional assistance from Blogger.not everybody responds positively. I won't publish the email that I have received recently, thanks to the Google Forums anonymous email delivery service.
But given further chance to reflect, there may be a way around the quandary. If you can't prove ownership of the blog, you can't have control of that blog. Sorry, that part can't be avoided. But you can start a second Blogger account, and a new blog, and you can link the new blog to the old one. You won't be able to go the other way, unfortunately.
But there it is, for you - a second chance. You don't have to pay a thing for the privilege - like all Blogger blogs, this one too is free. And, you get a new account, and a new password.
And maybe, with the new account, you can remember the password, and maintain the backdoor access? Be a responsible blogger, and encourage others to do the same.