i made a mistake. i changed wordpress and site address url but when i try to login wp-admin i could't. so i tried http://codex.wordpress.org/Changing_The_Site_URL#Changing_the_Site_URL
i did wp-config changes and it worked but i can't change anymore my url setting inside admin page. when i type without www i can't login my website but when i try to login with www but it says site couldn't find.
is it problem? with url settings or is it a Dns error? should i talk with domain company?