There are several reasons you might need to change another user's password in Windows 7 but most of the time it's because another user on your computer has forgotten their password.
Luckily for all of us with forgetful family members or roommates, Windows 7 makes it incredibly easy to change another user's password.
Important: Your Windows 7 user account must be configured as an administrator to change another user's password. See Tip #2 at the bottom of the page if you're trying to get access to another account in Windows 7 but you're not an administrator.
Follow the easy steps below to change another user's password in Windows 7:
Click on Start and then Control Panel.
Click on the User Accounts and Family Safety link.
Note: If you're viewing the Large icons or Small icons view of Control Panel, you won't see this link. Instead, click on the User Accounts icon and skip to Step 4.
Click on the User Accounts link.
Toward the bottom of the Make changes to your user account area of the User Accounts window, click the Manage another account link.
Click on the account that you want to change the password for.
Note: If the words Password protected are not listed under the user type then the user has no password configured, meaning he or she can log in to the account without a password. Obviously in this case 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 the Change the password link.
Enter a new password for the user in the first and second text boxes.
Entering the new password for the user twice helps ensure that you've typed the password correctly.
In the third and final text box, you're asked to Type a password hint.
Since you're probably changing this user's password because they've forgotten it, you can probably skip the hint. The user should change their password to something more private after they get access to their account again.
Click the Change password button to confirm the password change.
Warning: When you change a password in Windows 7 from outside the logged in account, which is what you're doing here, 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 users don't have EFS encrypted files and the loss of stored passwords isn't likely a big issue.
However, if this is a problem, the only way around it is to discover the original password using a true password recovery program like Ophcrack or Cain & Abel. Password resetting programs like ONTP&RE, PC Login Now, and Kon-Boot present the same loss of access issues so they're no help in this situation.
You can now close the User Accounts window.
Log off 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 7 password reset disk to avoid a problem like this in the future.
Not a Windows 7 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's password in Windows 7 but you're not an administrator then you can't use the method described above.
You can, however, 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 at all, let alone with an administrator account. You can then have the user change their own Windows 7 password.
Other options exist as well. See Help! I Forgot My Windows 7 Password! for some more ideas.