I've been getting 404s on public pages due to my directory setup, so I changed the default Resource URL in Administer >> System Settings >> Resource URLs from the default ([civicrm.files]?) to the URL for my civi directory.
I now can't get back to reset it to the default.
I've tried overriding the Resource URL in settings.php to:
http://mysite.org/mysite/wp-content/plugins/civicrm/civicrm/
but that doesnt work.
Any advice appreciated.