Logging in to my wordpress administration panel

I changed the WordPress Address (URL) from http://sitename.com to http://www.sitename.com and now I cannot login to my administartion panel. What should I do?

Thanks

 

To change from MySQL the address back to sitename.com ... only to delete www

 

Log into phpmyadmin. Navigate to the wp-options table. Change site url (near option ID 2) and change home URL (near option ID: 36).

 

You can make the edit in wp-config.php

If you are inexperienced with MySQL, do not use the advice above.

define('WP_HOME','[U]URL'[/U]);
define('WP_SITEURL','[U]URL'[/U]);

Code (markup):

Put that info in around your database name and you'll be fine