Internal server error

SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
#0 /home/ds393/web/ds-393.nios.ru/public_html/bootstrap.php(31): App_Db::factory() #1 /home/ds393/web/ds-393.nios.ru/public_html/index.php(11): require_once('/home/ds393/web...') #2 {main}