Quên mật khẩu root của MySQL

First things first. Log in as root and stop the mysql daemon. Now lets start up the mysql daemon and skip the grant tables which store the passwords.

mysqld_safe --skip-grant-tables

You should see mysqld start up successfully. If not, well you have bigger issues. Now you should be able to connect to mysql without a password.

mysql --user=root mysql

update user set Password=PASSWORD('new-password');
flush privileges;
exit;

Now kill your running mysqld, then restart it normally. You should be good to go. Try not to forget your password again.