Cannot connect to database !!

PDOException: SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: NO) in /home/tainstru/public_html/wp-content/plugins/search/php/Connection.simple.php:22 Stack trace: #0 /home/tainstru/public_html/wp-content/plugins/search/php/Connection.simple.php(22): PDO->__construct('mysql:host=loca...', 'root', '') #1 /home/tainstru/public_html/wp-content/plugins/search/index.php(5): dbConnect() #2 {main}