If you have privilege to access any computer using the administrator rights and want to change other users password without knowing his original password then the following description as how to do this is only for you... This is only a single command line instruction which is capable of reset any non-administrator password.
Here is a step-by-step instruction to accomplish this task
1. Open the command prompt (Start->Run->type cmd->Enter)
2. Now type net user and hit Enter
3. Now the system will show you a list of user accounts on the computer. For example you need to reset the password of the account by name ABC, then do as follows
4. Type in the command window open earlier net user ABC * and hit Enter. Now the system will ask you to enter the new password for the account. That’s it. Now you’ve successfully reset the password for ABC without knowing his old password. But don't forget to use asteric * when resetting the password.
So in this way you can reset the password of any Windows account at times when you forget it so that you need not re-install your OS for any reason.
So the next time if you want to have fun with any of your friends sharing the same computer you can make a joy by fooling him isn't this a quite funny idea let me know in comment section and don't forget to subscribe for the Feed-burner subscription if you want to receive the new updates.