MySQL_class: Database Error occured!

 CODE: 2002
 DESC: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
 FILE: index.php
 QCNT: 0
 INFO: Connect(): Connection to localhost failed!

Please inform trade@worldtradezone.com about this problem.
PHP v5.6.40 / MySQL Class v0.36