Trouble moving to SSL website

I have a wordpress site being used as an intranet. It has been running unsecured but I would now like to secure it. I have purchased an SSL and have other internal sites on the same server using the SSL (multi-domain) certificate. But for some reason I can’t get the wordpress site to work. And I’m now locked out of the site.

I started by following this tutorial on setting up an SSL. I changed my URL in the settings>general menu to “https://ap.mywebsite.com” but upon reloading the page I was locked out. I received the error

“The requested URL /wp-admin/options-general.php was not found on this server.

Apache/2.2.22 (Ubuntu) Server at ap.bpwgroup.com Port 1918″

I have changed settings in my NGINX and Apache settings (Nginx proxys to Apache) and I have two other websites on the same server that work with the SSL flawlessly. I was even able to get my wordpress URL to redirect to a different secured site. I was following this tutorial when I added the following line (line 4) to my Nginx config

server {
listen 80;
server_name yoast.com www.yoast.com;
return 301 https://yoast.com$request_uri;
}

I inadvertently forgot to remove the yoast.com from that code and replace it with my website. When I tried to visit my page it redirected me to yoast.com. So the redirect appears to be working.

Any ideas on what to try next?

Thanks,