Follow the steps below.
Start the MySQL server instance or daemon with the --skip-grant-tables option (security setting).
$ mysqld --skip-grant-tables
Execute these statements.
$ mysql -u root mysql
$mysql> UPDATE user SET Password=PASSWORD('my_password') where USER='root';
$mysql> FLUSH PRIVILEGES;
If you face the unknown field Password error above use:
update user set authentication_string=password('my_password') where user='root';
Finally, restart the instance/daemon without the --skip-grant-tables option.
$ /etc/init.d/mysql restart
You should now be able to connect with your new password.
$ mysql -u root -p
Enter password: my_password
Forrás:
https://superuser.com/questions/603026/mysql-how-to-fix-access-denied-f…
És persze mindenhol add meg ezt a jelszót, ahol kell (bár én külön felhasználókat hoznék létre korlátozott jogokkal).