Unable To Access Admin Dashboard Following Upgrade to HTTPS

Greetings!

I am working with a dedicated server running Ubuntu Linux 16.04.1. The webserver in use is Apache2.

Very recently, I upgraded the site security for our domain (www.windsorheightsvoices.net) from HTTP to HTTPS. Access to our site’s front page is unaffected (except for being secure), however access to the administrative dashboard for our site (https://www.windsorheightsvoices.net/wp-admin/) allows one to login, but then displays the following message:

<h2>Our services aren’t available right now</h2><p>We’re working to restore all services as soon as possible. Please check back soon.</p>Ref A: 6826E478EE7140F4BBA3BB8919927FF6 Ref B: E817F5D1289D2EB37101A6826860A68E

The research I have done so far suggests that this error message is due to the fact that I did not configure the WordPress software to be accessed via HTTPS prior to actually implementing the SSL Certificate. I can only plead ignorance and stupidity on my part for not having my waterfowl in a linear array before beginning this adventure!

I suspect there is a ‘backdoor’ method to configure WordPress to operate using HTTPS, but I have not found it yet among my search results and I am ever hopeful that some kind and intelligent soul that knows far more about WordPress than I do, will take me gently by the hand and walk me step-by-step through the process to get WordPress completely functional on our website.

I thank you in advance, whoever you may be!