This is an automated message generated by Facebook. Unfortunately, it doesn’t give a lot of information about what’s going on or how to fix the problem. This article describes a number of possible reasons for receiving this message and some steps you can take to try and resolve the problem.
“Nonce” is short for “number used only once”. Usually a nonce does not need to be secret or random, but it must not be reused with the same key. Sometimes the term is used for more general things, though.
In order to reset your Facebook password, you must have Facebook send a reset code via text message or email. Select the option that you want to use on the “Reset Your Password?” screen and click the “Send Codes” button. Open the text message or email you receive from Facebook to obtain your password reset code.