Automatically Disable Comments and Trackbacks in Old Posts

This function automatically closes comments and trackbacks after the specified number of days. Add the following to your functions.php file:

<?php function autoclose_comments() {
	global $wpdb, $tableposts;

	if (!isset($tableposts))
		$tableposts = $wpdb->posts;

		$age = '21 DAY';

		$date = $wpdb->get_var("SELECT DATE_ADD(DATE_SUB(CURDATE(), INTERVAL $age), INTERVAL 1 DAY)");
		$wpdb->query("UPDATE $tableposts SET comment_status = 'closed' WHERE comment_status = 'open' AND post_status = 'publish' AND post_date < '$date'");
}

function autoclose_trackback() {
	global $wpdb, $tableposts;

	if (!isset($tableposts))
		$tableposts = $wpdb->posts;

		$age = '21 DAY';

		$date = $wpdb->get_var("SELECT DATE_ADD(DATE_SUB(CURDATE(), INTERVAL $age), INTERVAL 1 DAY)");
 		$wpdb->query("UPDATE $tableposts SET ping_status = 'closed' WHERE comment_status = 'open' AND post_status = 'publish' AND post_date < '$date'");
}

add_action('publish_post',   'autoclose_trackback', 7);
add_action('edit_post',      'autoclose_trackback', 7);
add_action('delete_post',    'autoclose_trackback', 7);
add_action('comment_post',   'autoclose_trackback', 7);
add_action('trackback_post', 'autoclose_trackback', 7);
add_action('pingback_post',  'autoclose_trackback', 7);
add_action('edit_comment',   'autoclose_trackback', 7);
add_action('delete_comment', 'autoclose_trackback', 7);
add_action('template_save',  'autoclose_trackback', 7);

add_action('publish_post',   'autoclose_comments', 7);
add_action('edit_post',      'autoclose_comments', 7);
add_action('delete_post',    'autoclose_comments', 7);
add_action('comment_post',   'autoclose_comments', 7);
add_action('trackback_post', 'autoclose_comments', 7);
add_action('pingback_post',  'autoclose_comments', 7);
add_action('edit_comment',   'autoclose_comments', 7);
add_action('delete_comment', 'autoclose_comments', 7);
add_action('template_save',  'autoclose_comments', 7);
?>