URGENT! WP Salts update crashed website

The iTSec Change Salts feature will update the values for 4 + 4 authentication unique keys and salts in the wp-config.php file:

define( 'AUTH_KEY',         'put your unique 64 chars phrase here' );
define( 'SECURE_AUTH_KEY',  'put your unique 64 chars phrase here' );
define( 'LOGGED_IN_KEY',    'put your unique 64 chars phrase here' );
define( 'NONCE_KEY',        'put your unique 64 chars phrase here' );
define( 'AUTH_SALT',        'put your unique 64 chars phrase here' );
define( 'SECURE_AUTH_SALT', 'put your unique 64 chars phrase here' );
define( 'LOGGED_IN_SALT',   'put your unique 64 chars phrase here' );
define( 'NONCE_SALT',       'put your unique 64 chars phrase here' );

So make sure the wp-config.php file is ok.

+++++ To prevent any confusion, I’m not iThemes. +++++

https://api.www.ads-software.com/secret-key/1.1/salt/

You can generate salts here,
make sure there is only one definition for each constant in wp-config.php
no duplicates.

As for navigation 404 errors – try to revise/delete .htaccess file in your site top folder.

You can generate new one by going to Dashboard: Settings > Permalinks
then push Save (no need to change any settings), this will regenerate .htaccess with default rules.