Setting your WordPress Address Through wp-config.php
Since WordPress 2.2, you are able to define the WP_HOME through wp-config.php, the address that defines where people view your website, such as http://www.mywebsite.com . By setting it in wp-config.php, you will override the entry in the wp_options table of your Database, and will disable the URL field that appears in WordPress Dashboard » Settings.
In order to do this, you will need FTP/SFTP/SSH access to server.
Step 1) Connect to your server via FTP/SFTP/SSH
Step 2) Locate wp-config.php
Step 3) Open wp-config.php and add the following line, naturally replacing the values with where your site is located.
define( 'WP_HOME', 'http://example.com' );
Step 4) Save your changes.