I have forgotten my phone Password I have forgotten my Galaxy A7 2016 running android 5.1.1's password.
How do I open my phone without losing my files in device storage?
I found the answer for you here in this question

Quoting the answer given by @petercarlos : 


  Well, I would say I don’t think you can’t do anything about it because
  the forgot password button isn’t available with the Lollipop , now
  what you are left with is you can try unlocking your device with the
  help of your Google account i.e. Log yourself over the Google account
  you are using over Laptop/PC once done head over to the Android device
  manager and using it try unlocking your device remotely, also in order
  to do that your device must be connected to the Mobile Data or Wi-Fi
  network. And if you don't have the access then I guess you are locked
  out and the only thing you can do now is factory resetting your device
  by holding the Power+Volume down button.