I'm using CiviCRM version 4.7.17 on Joomla version 3.65. I changed my civicrm resource URL hoping it would load the civicrm.css file but instead I can no longer access my administration area. Please see phone of what I am receiving when I try to access the civiCRM component. How do I get back to the system settings area so I can change it back?
You could try to go the page directly
If you have sql access you could change them back. They are stored in civicrm_settings
SELECT name, value FROM civicrm_setting WHERE group_name = "URL Preferences"
You'll see the url between quotes in the value field.