Joomla Call to a member function setState()

Fro Joomla 2.5.x Paste the code on line  in helper.php file below

defined('_JEXEC') or die('Restricted access');

defined('_JEXEC') or die;
if( !class_exists("ContentModelArticles") ){
require_once JPATH_SITE.DS.'components'.DS.'com_content'.DS.'models'.DS."articles.php";
}

For Joomla 3.x – Paste the code below

defined('_JEXEC') or die('Restricted access');

if(!defined('DS')) define('DS', DIRECTORY_SEPARATOR);
if( !class_exists("ContentModelArticles") ){
require_once JPATH_SITE.DS.'components'.DS.'com_content'.DS.'models'.DS."articles.php";
}
if(!class_exists('ContentHelperRoute')) require_once (JPATH_SITE . '/components/com_content/helpers/route.php');