/etc/init.d/mysql stop
/usr/sbin/mysqld --skip-grant-tables
mysql> FLUSH PRIVILEGES;
mysql> SET PASSWORD FOR root@'localhost' = PASSWORD('votre_nouveau_mot_de_passe');
mysql> FLUSH PRIVILEGES;
mysql> exit
/etc/init.d/mysql start

// création user grant all
CREATE USER [IF NOT EXISTS] 'monadmin'@'%' IDENTIFIED BY 'monpass';
GRANT ALL  ON  *.* TO 'monadmin'@'%';