Here is another simple way through which you can reset the password of any non-administrator accounts. The only requirement for this is that you need to have administrator privileges. 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. Say for example you need to reset the password of the account by name John, then do as follows
4. Type net user John * 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 John without knowing his old password.