@ Reddazz........
How can u reset user password..
u don't know current password.........................?

If you don't know the user password than do it logged in as root with where USERNAME is obviously the name of the user whose password will be changed.

Hi,

Welcome to LQ!
Please do not resurrect old threads. Especially when query is for your potential question/problem(s). It would be best to create a new thread. Your post/query has been moved to a new thread.

FYI: I suggest that you look at 'How to Ask Questions the Smart Way' so in the future your queries provide information that will aid us in diagnosis of the problem or query.

cat /etc/passwd will give you a list of users in the system.
cat /etc/shadow will give you the passwords of those users (encrypted, of course).

Finding a user once you are inside the system is as simple as the first line, finding the password can be as time consuming as brute forcing for it or as simple as asking for it. Reseting it is as simple as TobiSGD stated if you have root access. If you want to disallow that account you can change the login shell in /etc/passwd for /usr/sbin/nologin. Or you can disallow password access by substituting the second field in /etc/shadown by ! or *.