Forgetting your Windows login password can be a troubling experience. You may fear losing your data and consider reformatting in order to gain access to your computer. However with the right software it's suprisingly easy to reset your password and take back control of your operating system.
The most effective tool I've found for resetting Windows login passwords is the Offline Windows Password and Registry Editor. I recommend the bootable CD image version as it's the easiest to use. You will need to download the ISO off of the website and then burn it to a CD as a disk image. Most burning programs such as Nero have a disk image burning option. From here you will need to restart your computer with your newly burnt CD in the disk drive. On most computers you will have to press F2 immedietly when the computer starts up in order to enter the BIOS. From here there will be a boot order option. Set it so that your computer boots from the CD drive first, before the system hard drive. Make sure to save and exit from the BIOS and the computer should restart and boot from the CD.
The software will start by asking if you want to turn on some optional features or if you prefer to boot the program without them. In most cases you won't need to do anything so just press ENTER to continue. From here you will need to select the disk drive where Windows is installed. In most cases it will be found on the largest partition. Just look at the total MB on the right hand side to gauge partition size. It is also usually disk "1" within this program. Once you know which drive to work from, enter it's value (ex. 1) and press ENTER.
You will then be asked to enter the path to the registry directory. 99% of the time it will be the default directory so press ENTER here again. From here press 1 and ENTER to continue to the password reset function. Now press 1 and Enter again to "Edit user data and passwords".
From here you will need to choose the applicable username which will have its password cleared. You will need to type the exact name of the username which you want to gain access to. For example if the username is "Peter" type Peter into the field and press ENTER. You will then be asked to clear the password, or change it among other options. I do not recommend changing the password from here as this has failed to work for me in the past. The best method is to press 1 and ENTER to clear the password and then set a new one once you're back in Windows.
Your password should now be cleared so press "!" and then ENTER. Then press "q" and ENTER to exit the program. You will need to make sure you save your changes to the disk otherwise the password will not be reset. Thus press "y" for yes and ENTER when asked to write the files back to the disk. Lastly, you will be asked if you want to run the program again. Hit "n" for no and ENTER and when asked press CONTROL-ALT-DELETE to reboot.
You can remove the disk after the program has shut down or change your boot order back in the BIOS to boot back into Windows. Congratulations! Your password should now be reset and you will be able to log back into Windows!