1. Reboot the PC(select reboot as you log out the of the GUI) or power up a usual.
   

   Soon you see the graphical boot loader on screen that shows the name of the operating systems you can boot. If your system runs with LILO boot loader, press Ctrl+X and at the boot prompt type linux single and press enter. Then proceed to step 4.

2. If you have more than one operating system installed, use the arrow key to select linux as operating system, then press the A key.

GRUB prompts you for commands to add to its defualt boot command.

3. Press the spacebar, type the following, and press enter:

single

Linux starts up as usual but runs in a single-user mode that do not require you to log in. After linux starts, you will see the following command line prompts that ends with a hash mark (#), similar to the following :

sh-2.05b#

4. Type the paswrd command to change the root password as follows:

sh-2.05b# passwd
Changing password for root user.
New password:

5. Type the new root password that you want to use (it doesn’t appear on screen) and then press enter.

Linux asks for the password again, like this:

Retype new password:

6. Type the new password again, and press enter.

If you enter the same password both times, the passwrd command changes the root password.

7. Now type reboot to reboot the PC.

After linux starts, it displays the familiar login screen. Now you can log in as root with the new password

Here are the steps when you found yourself in this situation.

1. Kill the server process.
% kill pid
(where pid is the process id. Do not use kill -9 unless absolutely
necessary, as this may damage your table files)

2. Run safe-mysqld with the –skip-grant-tables command line option.
(This instructs the MySQL server to allow unrestricted access to
anyone) NOTE: restrict all remote access before issuing this command
% safe-mysqld --skip-grant-table

3. Change root password
mysql > use mysql;
mysql > update user set password = password('newpassword') where user
= 'root';

4. Disconnect and instruct the mysql server to reload the grants
tables to begin requiring passwords.
% mysqladmin flush-privileges

“That does it — and nobody ever has to know what you did. As for
locking your keys in your car, you’re on your own there.”

Must have for php-mysql beginners developers.