Only your Service Provider can help you and they may be able to tell you where it was when last turned on. You also need to notify them of the loss because you are liable for any bill the finder or the thief is running up in mobile data and calls.
It's also worth a visit to the local Police Station - some people still take things they find there.
This old thread is closing now but if you need further help, please start a thread of your own. Don't include your IMEI reference. It's best only you know that.