How Can I Change My Facebook Password Back to the Old One?by Vanessa Padgalskas
Facebook allows you to change your current password back to your former password. Your password must be at least six characters long. To have a secure password, Facebook recommends that it include a variety of character types, including numbers, capital and lowercase letters, and punctuation marks. In addition, Facebook recommends that your password not include words from the dictionary.
Log into your Facebook account.
Click "Account" in the top-right corner of your Facebook homepage and then click "Account Settings."
Click "Change" to the right of "Password."
Enter your current password, your new password (your former one) and then type your new password again to confirm it. Click "Change Password" to change your password back to your old one.