WordPress Address Mistake

I went to settings>general and changed the wordpress address and the site address to another domain name I had.

You can do that, but that only tells your database what to expect coming in and what to tell WordPress to use for finding things. So to make that work, you next have to use cPanel or whatever to send the previous domain elsewhere and to send the new one to the installation now expecting it.

To fix things…

/*-either-*/
/** @ near top of wp-config.php /*toggle on/off*
define('WP_HOME','http://domain.com');
define('WP_SITEURL','http://domain.com');
/*-or-*/
/** @ near top of wp-config.php /*toggle on/off*
define('WP_HOME','http://www.domain.com');
define('WP_SITEURL','http://www.domain.com');
/*-end-*/

Select the two lines you want to use, edit them and then temporarily add a slash following the /*toggle on/off* just above them to un-comment them.