Blogger (Google) accounts are anonymous, requiring only access to one email address.  Blog access is token based.  The token is attached to a Google account when a blog is created, or when a blog member is added.

 

Anonymous blog ownership gives you the ability to write about whatever is on your mind, without fear of anybody connecting a blog with your real life identity - if you don't intentionally let that happen.  But anonymous blog ownership comes with a price. 

If you lose access to the Google account, and to the email address supporting that account, you lose access to the blog.

Blogger has no other automated procedure to verify that you are the legitimate owner of your blog.  Since they don't want some stranger writing and asking for access to your blog, they can't automatically believe you when you write and ask for access to your blog.  You have to prove ownership of your blog.  Don't blame Blogger, when you can't prove ownership of your blog.

Blogger has stated that blogs are forever, which by extension means that your anonymity, and security of your blog, will be preserved forever.  If you can't prove ownership of your blog by automated means, your only hope for regaining access to your blog is by the Blogger Contact Form.  Be patient and polite now, you need them on your side.