get monty widget

echo '<ul class="list-no-mark">'; wp_get_archives( array( 'type' => 'monthly', 'show_post_count' => 0,'post_type' => 'change here' ) ); echo '</ul>';
$output='<select name="archive-dropdown" onChange='document.location.href=this.options[this.selectedIndex].value;'> <option value=""><?php echo attribute_escape(__('月を選択してください')); ?></option>';
$output .= wp_get_archives (array(
    'post_type' => 'information',
    'type' => 'monthly',
    'show_post_count' => '0'
    ));
$output .='</select>';
return $output;