If you've forgotten your administrator password for a Windows installation running on your Mac, don't despair. There are a few ways to reset it.The first and easiest method is to use a utility called Kon-Boot. Kon-Boot is a program that allows you to login to a computer without knowing the password. It works by modifying the system files that store the password, so that the password is not checked when you login.To use Kon-Boot, you'll need to create a bootable CD or USB drive. The Kon-Boot website has instructions for doing this. Once you've created the bootable media, boot your Mac from it. Kon-Boot will load and you'll be able to login to Windows without entering a password.Once you're logged in, you can change the password for the account from the Control Panel. Kon-Boot is a free program, but it only works on Windows XP and earlier. If you're using Windows Vista or 7, you'll need to use another method.The next method is to use a program called Offline NT Password & Registry Editor. This program works by editing the registry, which is where Windows stores information about user accounts.To use Offline NT Password & Registry Editor, you'll need to download the program and burn it to a CD or USB drive. Then boot your computer from the CD or USB drive. The program will load and you'll be able to select the Windows installation you want to edit.Select the "Edit user data and passwords" option and then choose the account you want to change the password for. Enter the new password and then reboot your computer.If you're using Windows 8 or 10, the process is a bit different. Microsoft has introduced a new feature called Trusted Boot, which makes it more difficult to modify the system files that store passwords.However, there's a program called PCUnlocker that can bypass Trusted Boot. To use PCUnlocker, you'll need to create a bootable CD or USB drive. Then boot your computer from the CD or USB drive.The program will load and you'll be able to select the Windows installation you want to unlock. Select the "Unlock with password" option and enter the password you want to use. Then reboot your computer and you'll be able to login without a password.If you don't have a Windows installation running on your Mac, you can still reset the password for an account by using the Recovery HD. The Recovery HD is a hidden partition on your hard drive that contains tools for troubleshooting and repairing your Mac.To access the Recovery HD, restart your Mac and hold down the Option key while it's booting. When the boot menu appears, select the Recovery HD.Once the Recovery HD has loaded, open the Terminal from the Utilities menu. In the Terminal, type "resetpassword" and press Enter.This will open the Reset Password utility. Select the account you want to reset the password for and enter the new password. Then reboot your computer and you'll be able to login with the new password.If you don't have a Recovery HD, you can still create a bootable USB drive or CD with the OS X installer. To do this, download the OS X installer from the App Store.Once the download has finished, launch the installer and choose the "Create a bootable installer drive" option. Select the USB drive or CD you want to use and follow the prompts to create the bootable media.Once the bootable media has been created, restart your Mac and hold down the Option key while it's booting. When the boot menu appears, select the USB drive or CD.The OS X installer will load and you'll be able to choose the "Reset Password" option from the Utilities menu. Follow the prompts to reset the password for the selected account.If you've forgotten your administrator password and you're using a Mac, don't worry. There are a few different ways to reset it. You can use a utility like Kon-Boot or Offline NT Password & Registry Editor, or you can use the Recovery HD.