Não conectado ao Banco de Dados!

PDOException: SQLSTATE[HY000] [1045] Access denied for user 'usuario-do-banco'@'localhost' (using password: YES) in /home/hostarrochat/public_html/sistema/conexao.php:18 Stack trace: #0 /home/hostarrochat/public_html/sistema/conexao.php(18): PDO->__construct('mysql:dbname=no...', 'usuario-do-banc...', 'senha-do-banco') #1 /home/hostarrochat/public_html/cabecalho.php(1): require_once('/home/hostarroc...') #2 /home/hostarrochat/public_html/index.php(1): require_once('/home/hostarroc...') #3 {main}
Fatal error: Uncaught Error: Call to a member function query() on null in /home/hostarrochat/public_html/sistema/conexao.php:31 Stack trace: #0 /home/hostarrochat/public_html/cabecalho.php(1): require_once() #1 /home/hostarrochat/public_html/index.php(1): require_once('/home/hostarroc...') #2 {main} thrown in /home/hostarrochat/public_html/sistema/conexao.php on line 31