Can not edit my “Home-Font” page

When I click “Edit” under “Pages”-“Home-Font page”, it will give me a page of text”The site is experiencing technical difficulties. Please check your site admin email inbox for instructions.”
But the “admin email” is still my old web developer’s email who is out of business already. I try to change it, the link to confirm the change in the confirmation email sent by WordPress is “NOT FOUND”.
All the other pages are fine to edit.
Please help…I need to edit a link address on my homepage.
Thanks a lot.

The page I need help with: [log in to see the link]