Step:1 Stop mysql service
# /etc/init.d/mysql stop
Step:2 Start to MySQL server without password:
# mysqld_safe --skip-grant-tables &
Step:3 Connect to mysql server using mysql client:
# mysql -u root
Step:4 Setup new MySQL root user password
mysql> use mysql;
mysql> update user set password=PASSWORD("NEW-ROOT-PASSWORD") where User='root';
mysql> flush privileges;
mysql> quit
Step:5 Stop MySQL Server:
# /etc/init.d/mysql stop
Step:6 Start MySQL server and test it
# service mysqld start
# mysql -u root -p