ANSWER:
If you already lost your phone or somebody stole that, this trick won't help you. because firstly, you need to install a program on your phone!
If you bought a new android phone, I extremely suggest you to DO THESE INSTRUCTIONS.
You need to install a program on your phone to protect it from loosing it in the future…
1. First, download and Install Phone Locator PRO–MobiUcare on your Android phone.
2. Then go to www.mobiucare.com and activate and sync the program to the website.
3. This is the only program that really works even if somebody change the sim card of the phone or put the phone on the Air Plane mode.
on my next question I will show you a trick that you can find your stolen phone.(that may help you even if you already lost your phone!)