Three ways to change your mysql password and how to forget your root password

Method 1: Use the SET PASSWORD command

mysql -u root
mysql> SET PASSWORD FOR 'root'@'localhost' = PASSWORD('newpass');

Method 2: Use mysqladmin

mysqladmin -u root password "newpass"

If root has already set a password, do the following

mysqladmin -u root password oldpass "newpass"

Method 3: Edit the user table directly with UPDATE

mysql -u root
mysql> use mysql;
mysql> UPDATE user SET Password = PASSWORD('newpass') WHERE user = 'root';
mysql> FLUSH PRIVILEGES;

You can do this when you lose your root password

mysqld_safe --skip-grant-tables&
mysql -u root mysql
mysql> UPDATE user SET password=PASSWORD("new password") WHERE user='root';
mysql> FLUSH PRIVILEGES;