Will this work to fix the problem in reverse:
OPTION 2. If you forget to change the WordPress Address and Blog Address, you will be unable to change it using the wordpress interface. However, you can fix it if you have access to the database. Go to the database of your blog and find the wp_options table. This table stores all the options that you can set in the interface. The WordPress Address and Blog Address are stored as siteurl and home (the option_name field). All you have to do is change the option_value field to the correct URL for the records with option_name=’siteurl‘ or option_name=’home‘.
Suppose you accidentally changed the URIs where you cannot move the files. (but still can access the login page, through a redirection or something)
wp-login.php can be used to (re-)set the URIs:
//FIXME: do comment/remove these hack lines. (once the database is updated)
update_option('siteurl', 'http://your.domain.name/the/path' );
update_option('home', 'http://your.domain.name/the/path' );
You're done. Test your site to make sure that it works right. If the change involves a new address for your blog, make sure you let people know the new address, and consider adding some redirection instructions in your .htaccess file to guide visitors to the new location.
Changing The Site URL also provides the details of this process!
Where do I add the code to the wp-login.php?