Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists code example

Example: can't connect to local mysql server through socket '/var/run/mysqld/mysqld.sock'

# this saved my ass
# first  you must perform a graceful shutdown of the server from the command line rather than powering off the server
shutdown -h now

# an additional method for getting it back up again when you run into this problem is to move mysql.sock

# to centos
mv /var/lib/mysql/mysql.sock /var/lib/mysql/mysql.sock.bak

# to ubuntu
mv /var/run/mysqld/mysqld.sock /var/run/mysqld/mysqld.sock.bak

# restart mysql
service mysqld start