You can't locate the phone on your own unless you had an app or service for tracking on it before it went missing. You can contact your service provider/carrier and they may be able to tell you where it was last used, or at least an area, but even they can't tell you exactly where it is.
Leaving the service on, and not reporting it stolen, to the service provider/carrier is a really bad idea. You need to get them to turn off the service so you don't get charged for anything the other party does.
To be honest, once a device is gone, it is rarely if ever recovered/returned.