Warning: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /usr/w/var/www/html/html/library/mysql.php3 on line 56

Warning: MySQL Connection Failed: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /usr/w/var/www/html/html/library/mysql.php3 on line 56
[Connection attempt failed] ( 2002 : Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) )