If this is the error you are getting then one of the solutions is to reset your root password on the MySQL database server.

$ pkill mysql
$ sudo mysqld --skip-grant-privileges
$ mysql

At this point you get the mysql command shell. You will need to update the root password and flush the table when you reset the password.

mysql> set UPDATE mysql.user SET Password=PASSWORD('YOUR_NEW_PASSWORD') WHERE User='root';
mysql> FLUSH PRIVILEGES;

Now that you’ve flushed your passwords, just restart your mysql daemon.

$ sudo pkill mysqld
$ sudo /etc/init.d/mysqld start
$ mysql -u root -p
Enter Password: YOUR_NEW_PASSWORD
mysql>

You should be all set now!