Changed Resource URL setting, now can't access Civi on Wordpress
If I understand your question correctly, you are asking how to return the settings back to default.

I believe that the default settings for WordPress (in Administer >> System Settings >> Resource URLs) are as follows:


CiviCRM Resource URL: [civicrm.root]/
Image Upload URL: [civicrm.files]/persist/contribute/
Custom CSS URL: (blank)
Extension Resource URL: [civicrm.files]/ext/


You would typically only need to override the Resource URL in civicrm.settings.php if you have moved your site. I suggest that you set this back to how it was previously.

You may want to post a separate question about the problems you are having with 404s if this is still an issue.