You might want to try this:
1.On a computer or other mobile phone, visit: google.com/android/devicemanager
2.Sign in using your Google login details that you also used on your locked phone.
3.In the ADM interface, select the device you need to unlock (if it isn’t already selected).
5.In the appearing window, enter a temporary password. You don’t have to enter a recovery message. Now click ‘Lock’ again.
6.If it was successful, you should see a confirmation below the box with the buttons Ring, Lock and Erase.
7.On your phone you should now see a password field in which you should enter the temporary password. This should unlock your phone.
8.Now, before you go on with your life, go to your phone’s lock screen settings and disable the temporary password.