If you are NOT using WordPress MultiSite add the following in wp-config.php.
define( 'WP_HOME', 'http://klenotnictvi-benesov.cz' );
define( 'WP_SITEURL', 'http://klenotnictvi-benesov.cz' );
If you ARE using WordPress MultiSite you will need to access the database directly and edit the wp_options table and change “siteurl” & “home” to the correct url.
Here is more info on changing the site URL