Forgot phone unlock password and its gmail account for PrismII phone

@syaoran​ is absolutely correct! You will need to figure out which e-mail address you used for the particular device.  I was trying to think what would be the best way to figure this out and if it were me, I would try using Android Device Managerhttps://www.google.com/android/find.  If you do indeed have more than one Gmail account, I would log in to the site using each one and see which devices populate.  I can't guarantee that it'll work, but it'll be your best bet for figuring out which e-mail address is associated with the phone. 

Oh, and please note that if you can't remember the password to a particular account and you reset it, the phone may lock you out for 24-72 hours (your mileage may vary based on your version of Android) after the change.