MySQL Error:2002

Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

• [/home/.sites/75/site8/web/sys/lib/mysql.class.php @ 287] printerror(Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2),MySQL Error:2002)
• [/home/.sites/75/site8/web/sys/lib/mysql.class.php @ 80] database->oops(Could not connect to server: localhost.)
• [/home/.sites/75/site8/web/sys/core.php @ 29] database->connect()
• [/home/.sites/75/site8/web/contactus_1.php @ 1] include(/home/.sites/75/site8/web/sys/core.php)