Hi,
login as root user then stop mysql and start mysqld with --skip-grant-tables (e.g. /usr/sbin/safe_mysqld --skip-grant-table).
Login to the mysql server wit "mysql -h localhost mysql"
change the root password (update user set password=password('the new password') where user='root').
Flush the privileges with "flush privileges".
stop the database
start the database as usual