ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

Problem occurs when running mysql in an ubuntu box. I did the following checking to solve it:

1) Check if mysql is properly installed. Make sure that you have installed both server and client.

$ apt-get install mysql-server mysql-client

2) Check if both server and client are running

$ ps -ef | grep mysql

This should result to something like this:

root      8055     1  0 15:13 ?        00:00:00 /bin/sh /usr/bin/mysqld_safe
mysql     8173  8055  0 15:13 ?        00:00:00 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --skip-external-locking --port=3306 --socket=/var
/run/mysqld/mysqld.sock
root      8174  8055  0 15:13 ?        00:00:00 logger -p daemon.err -t mysqld_safe -i -t mysqld
user      8808  6327  0 15:34 pts/0    00:00:00 grep mysql

3) See if there is a proper account for accessing mysql.

try:

$ sudo mysqladmin password newpassword

then enter newpassword on

$ sudo mysql -u root -p

That's all I did. Actually doing the first one solve my problem.