Changed URL now can't log in to my dashboard

Hello, After figuring out how to access phpMyAdmin I changed my URL and now am unable to login to my WP dashboard. When I try I get a message “Unable to open https://myURL/. The Internet site reports that the item you requested could not be found. (HTTP/1.0 404)

Where: myURL is the original URL of my website.

I have tried logging in using the changed URL as myURL and get the same message.

I used the specific step by step procedure in the WP Codex topic “Changing the URL directly in the database” Is there something more I should have done?

Having no knowledge of how all this works I am now stuck not knowing what to do. I simply want to change the URL and be able to continue on as before when everything was working fine.

any assistance gratefully appreciated.

Thank you