There are lots of reasons you might want to change another user's password in Windows Vista but most of the time it's because someone who uses your computer has forgotten their password.
Luckily, Windows Vista makes it really easy to change another user's password.
Important: Your Windows Vista account must be configured as an administrator if you want to change another user's password. See Tip #2 at the bottom of the page if you're trying to change the password to another account in Windows Vista but you're not an administrator.
Follow the easy steps below to change another user's password in Windows Vista:
Click on Start and then Control Panel.
Click on the User Accounts and Family Safety link.
Note: If you're viewing the Classic View of Control Panel you won't see this link. Instead, double-click on User Accounts and then skip to Step 4.
Click on the User Accounts link.
Near the bottom of the Make changes to your user account area of the User Accounts window, click on Manage another account.
Click on the account that you need to change the password for.
Note: If Password protected is not listed under the account type then the user has no password set, meaning he or she and can log in without a password. Obviously then there's nothing to change so just let the user know that they don't need a password and can set one up themselves next time they log in.
Under the Make changes to [username]'s account heading, click Change the password.
Enter a new password for the user in the first two text boxes.
In the third text box, you're asked to Type a password hint. You can skip this.
Since you're probably changing this user's password because they've forgotten it, the user should change their password to something more private immediately after getting access back. No need to setup a hint that won't be valid in five minutes anyway.
Click the Change password button to confirm the change of password.
Warning: When you change a password in Windows Vista from outside the logged in account, which is what you're doing in this situation, the user you're changing the password for will lose all access to EFS encrypted files, personal certificates, and any stored passwords like those for network resources and website passwords. Most people don't encrypt files and the loss of stored passwords probably isn't a big deal to most.
However, if this does present a problem, the only way around it is to discover the original password using a password recovery program like Ophcrack or Cain & Abel. Password resetting programs like ONTP&RE, Kon-Boot, and PC Login Now cause the same loss of access issues so they're not better options in this situation.
You can now close the User Accounts window.
Log off Windows Vista or restart the computer and then have the user log in to their account with the password you chose for them in Step 7.
Once logged in, have the user create a Windows Vista password reset disk to avoid a problem like this in the future.
Not a Windows Vista user? See How Do I Change Another User's Password in Windows? for specific instructions for your version of Windows.
If you need to change another user's password in Windows Vista but you're not an administrator then you won't be able to use the method described above.
However, you can use a free Windows password recovery program to crack or reset the password. With most of these programs, you don't need to have access to Windows Vista at all. You can then have the user change their own Windows Vista password themselves.
There are also other options to consider. See Help! I Forgot My Windows Vista Password! for some more ideas.