It often happens. You are given the job of administrating a MySQL server where the root password was lost.
What to do? Here is the solution I found in Internet at the link below. Thanks for the useful tip.
http://www.cyberciti.biz/tips/recover-mysql-root-password.html

by Vivek Gite · 121 comments

You can recover MySQL database server password with following five easy steps.
Step # 1: Stop the MySQL server process.
Step # 2: Start the MySQL (mysqld) server/daemon process with the –skip-grant-tables option so that it will not prompt for password.
Step # 3: Connect to mysql server as the root user.
Step # 4: Setup new mysql root account password.
Step # 5: Exit and restart the MySQL server.

Here are commands you need to type for each step (login as the root user):
Step # 1 : Stop mysql service

# /etc/init.d/mysql stop
Output:
Stopping MySQL database server: mysqld.

Step # 2: Start to MySQL server w/o password:

# mysqld_safe --skip-grant-tables &
Output:

[1] 5988
Starting mysqld daemon with databases from /var/lib/mysql
mysqld_safe[6025]: started
——————————————————–
Well for some unknwon reason mysql server didn’t start (in Debian Lenny)
So to solve this I modified the start/stop script (/etc/init.d/mysql) as follows:
Around line: 100 (Addition is in bold here)
This way it retained its environment etc. to be able to start…and it worked 🙂
———————————————————–
...........
# Start daemon
log_daemon_msg "Starting MySQL database server" "mysqld"
if mysqld_status check_alive nowarn; then
log_progress_msg "already running"
log_end_msg 0
else
/usr/bin/mysqld_safe --skip-grant-tables > /dev/null 2>&1 &
# 6s was reported in #352070 to be too few when using ndbcluster
for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14; do
..............

————————————————————

Step # 3: Connect to mysql server using mysql client:

# mysql -u root
Output:

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1 to server version: 4.1.15-Debian_1-log

Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.

mysql>

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
Output:

Stopping MySQL database server: mysqld
STOPPING server from pid file /var/run/mysqld/mysqld.pid
mysqld_safe[6186]: ended

[1]+ Done mysqld_safe –skip-grant-tables

Step # 6: Start MySQL server and test it

# /etc/init.d/mysql start
# mysql -u root -p