If you've forgotten how to unlock your screen, you'll have five attempts to try and do so. If this fails, you can unlock your phone using these steps:
Your screen will now be unlocked.
Note: You need to have a Google account on your phone for these steps to work. If you haven't set up a Google account, you'll need to reset your phone. The reset will clear all the data stored on your phone, data that’s stored on your SIM is safe.
To reset your phone:
The reset will now be complete.