Welcome to Android Central! If it was stolen, I would report it to your wireless carrier, so they can blacklist the IMEI. That way, no one else can make calls using that phone.
The only way you can try to locate the phone is using Android Device Manager (at google.com/android/devicemanager), but this requires the phone to be on, and connected to the web. It also won't work if whoever has it did a factory reset.
Also report it to your local police. Some police departments take a cellphone theft seriously as a theft, and will actually try to find it. Also, any insurance you may have on the phone may want a copy of the police report.
BTW, once you report the phone as stolen to your carrier, you may have a hard time getting it unlisted as stolen if you get it back. Check with them about how to make that easiest at the time you go to them to report it stolen. (They may make a copy of some identification, which can then later be used to unlist the IMEI.)
my sons S5 was taken we had just taken it off from ATT so it was not active but i have the imei . we wanted it for his backup phone. i hate how people take advantage of his nice nature. being he has aspbergers. how can i possibly track it ATT said they cant do anything
Welcome to Android Central! Sorry to hear that -- some people just plain suck. But if I may ask, why do you want to track the phone? Do you actually hope to recover it? If you've already reported it as stolen, AT&T has already blacklisted it, which means no one can use it as a phone any more (including you, if you somehow recovered it).
If you still want to locate it, your main options would be Android Device Manager and Samsung's Find My Mobile. Have you tried either of those?