problem Switching from static to blog Front Page

I started my site with a static Home page, and decided to switch to having a blog on the front page. So I drafted a post. A preview showed that everything appeared to be in order. I deleted the Hello World post, since it seemed to be there only as a “how to.”

Then I switched from a static Front Page to a “your latest posts” Front Page (Dashboard -> Appearance -> Customize, clicked Static Front Page) and then published the post.

The post doesn’t show anywhere on my site, not even on the static page that had been the Home page.

When I click on Home in the Nav bar, I get a Not Found page.

What went wrong? Should I have used the Hello World post for my first post? If so, how do I get it back?