I've got a 3 year old Samsung and it has "find my mobile" installed in it and you can also get this from Google. Your phone simply needs a GPS in it which most have these days. You simply get on your home computer, log in and it shows on a map where your phone is. Google also offers this which I've also tried. With Google, you can not only locate your phone, you can also remotely lock your phone so no one can use it, have your phone ring in case you know it's at home somewhere and even erase your device. I've tried this (locating the phone) at home and sure enough it showed my phone on a map being at my address. I also have tried having it simply ring and that worked too (actually I really couldn't find my phone at home, it was in the garage!)
Edited to say that, of course all of the above only works if the battery hasn't died on your phone.