Not working

In installed and activated the custom wp-admin URL plugin on WordPress 4.2.1. It worked until I had to change a setting/general site URL to add a www to the site URL. Started getting errors error messages at the login screen, something about a file not found. Error coming from the hot access. I uninstalled the plugin an installed it again. Now it won’t work at all. In fact neither did the wp- admin so I edited the .htaccess file deleting the two lines for wp-admin.

Any suggestions? Would like to get this installed and working properly.

https://www.ads-software.com/plugins/hc-custom-wp-admin-url/