ERROR (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock'
This is a commonly seen error in database driven sites. The same error can show up when a connection or restart for MySQL server is attempted via commandline.
A quick check of the log files may reveal that the actual error faced by MySQL server is “InnoDB: Unable to lock ./ibdata1, error: 11”.
In our role as Outsourced Tech Support for web hosting providers, database errors are one major category of issues we resolve for the customers.