An appropriate representation of the requested resource /wp-login.php could not

I’m watching a WordPress tutorial which recommended NOT having admin as a user. I’d already set it up that way but learned I could add a new user, log out, log in as the new user name, and then delete the user “admin.” Since I did that, I can’t get into my site.

I’m new to this. It looks like by deleting the admin user, I also deleted resource /wp-login.php from the server.

Where and how can I add it? (If that indeed is the problem.)

Thank you so very much for your help.

-sj