Stolen phones can be locked if you can’t track down the phone or retrieve the stolen device by any means such as retrieving your stolen phone using gmail account and some other means that are indeed a valid way of retrieving a stolen phone.
For the fact that you can’t access your stolen phone, you still have the chance of locking it from your end. First and foremost you need to read how to track a stolen Android phone so that you will know what to do if you have not misplaced your phone or if the device has not been stolen.
Following the steps below will explain in detail how you can easily lock your phone using your Google account.
1. Login to Google Android device manager with your Gmail detail (the exact Gmail account you used to track the phone).
2. If you have more than one Android phone added to your Google Android manager, click on the name of the phone and hit the lock icon.
3. After you have clicked on the lock button as indicated above, enter your new password differs from your previous password and you Gmail password. Only the password section is compulsory while others are optional and you may let them be as they were and click on lock but for effectiveness enter exactly what you would love to display as a warning on the screen of the phone and then click on lock.
4. After you have clicked the lock button from the latter step, an auto lock will be sent to the phone screen and it will lock instantly. See an example below.
That is just the simple trick you can use to lock your stolen Android phone using Gmail account without stress.