unknown password when trying to restore my data from the previous iphone.

Hello everybody, I just got an iphone 6s and i'm trying to restore my backed up data from my previous iphone via itunes, however when trying to restore the data, itunes prompts me with a required password, which is neither my apple id password nor my iphone pin, I have literally tried every single password that I can think off, and it still won't allow me to restore my data. Any help would be appreciated.