Suppose,you are working on someone's computer and you want to change its password..Then open CMD.type.."net user" then the administrator account name and the current account name will be given....Now,suppose the account name is intel then for changing its password type..

net user intel *

Then press ENTER.It'll say to type a new password...type the new password..Then confirm it also..And then press ENTER..
You can also change the administrator account passowrd with this..
Important :-You won't see the password while typing ,but it really works..
Try this..
Have fun....