Lost SharePoint Farm Passphrase
It’s okay… it happens. You can’t retrieve it, but you can reset it using PowerShell. Make sure that the account you are logged in as is: (1) a farm admin and (2) local admin on server
$passphrase = ConvertTo-SecureString -asPlainText –Force
Set-SPPassPhrase -PassPhrase $passphrase –Confirm
More info on TechNet: https://technet.microsoft.com/en-us/library/ff607568.aspx