A password reset disk and another valid account with admin rights are both the easier way to reset a lost user password. But it seems that those are out of your reach, So, you'd better to use password reset/recovery software, not to re-install your Windows. Ophcrack is a most used free password recovery software, which can help you solve the problem if your lost password length is not longer than 14 characters. If you have trouble to use Ophcrack, you can try another shareware Rekeysoft Windows Password Recovery, which is more easier and efficient.
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