I installed WP just last week and was messing around with Site address URL settings – and broke access to my website. I changed wp-config.php file as above, restoring old site URL and Home and this gave me some connectivity once more, but then unable to login. In current version it seems you need to modify the mysql db to fix.
I had a simple mysql dbsetup, but didn’t want to use phpmyadmin. Luckily found this guide which has simple mysql instructions to fix;
https://www.networkforensics.us/2010/11/update-wordpress-home-url/#comment-566
So might save someone some time if they have simple needs like me.
