Suddenly ,I have just got password for root access despite I did not install it.
Is this possible that computer got password suddenly today.?
How do I fix this problem?

>> Suddenly ,I have just got password for root access despite I did not install it.
Is this possible that computer got password suddenly today.?
How do I fix this problem? <<

Not sure what the question is here - have you forgotten your root password? - if so, boot into single user mode via:

For LILO:

At the LILO prompt, when it says "boot:" type:

linux single

and then type

passwd

you can create a new root password here.

(however - if you just want to change your root password normally then su to root user in an xterm and type passwd)