If the user was already logged on or if there was no password, easy to do this.
Need to log on as another user with admin rights, and change the password on your account. There should be a user called Administrator, many times the password is blank form the factory, can try that.
Of course, how obvious, he was already logged on, provided it is his computer to begin with. Guess I am just a bit suspicious about assisting people having to get back into their system, and this was certainly a new twist !