wp_nav_menu changed to wp_page_menu

Question

I've styled my navigation menu with the classes of wp_nav_menu .menu_item , .sub_menu etc.When i added a new page suddenly the whole menu was ruined the classes where changed to .page_item, .children the ul was wrapped with a div container.I checked the code and the function wwas wp_nav_menu...What should I do to get the old menu style?

Edit

wp_nav_menu( array( 
    'theme_location' => 'main_menu', 
    'container' => '', 
    'menu_class' => 'menu'  
) );

Answer 1

Found the answer i've added changed the wp_nav_menu args to this:

    wp_nav_menu(array(
        'theme_location'  => '',
        'menu'            => '',
        'container'       => '',
        'container_class' => '',
        'container_id'    => '',
        'menu_class'      => 'menu',
        'menu_id'         => '',
        'echo'            => true,
        'fallback_cb'     => 'wp_page_menu',
        'before'          => '',
        'after'           => '',
        'link_before'     => '',
        'link_after'      => '',
        'items_wrap'      => '<ul id="%1$s" class="%2$s">%3$s</ul>',
        'depth'           => 0,
        'walker'          => ''
    ));