Android Device Manager is the feature of Google which allows a user to find his/her lost phone/tablet location.Android Device Manager does not only helps to find lost phone/tablet but also enables a user to erase data of his/her lost phone and to lock it remotely.But, you will be able to find your Lost phone only if you had activated Android Device Manager in it, if you had not activated it in your lost phone, then you will not be able to find the location of your lost phone.But, you should activate Android Device Manager to your phone/tablet so that in future if you lose your phone, you may find it’s location.Well, to activate Android Device Manager in your phone/tablet, go to Settings>>Location>>and enable Google’s Location service And Click on Agree. Now, go to google settings >> Security and click on remotely Locate This Device.
Now, if you lose your phone in future, simply type Android Device Manager in Google and click on the first result shown or click on this link google.com/android/devicemanager.
After clicking on it, you will have to enter your Gmail Id which you used in your phone/tablet to access Google.After Logging in, a window will open, having Several option like Ring, Lock, Erase and Locate Device.Click on Locate Device and the current location of your phone/tablet will be shown on Google Map.
You can also use other options of Android Device Manager like you can Ring your Phone even if it is on silent mode.Just Click on Ring option.
You can Erase your Phone data.Click on Erase.Simple.
The Last thing you can do with the help of ADM is to lock your phone.Just Click on Lock option.