Lost samsung s3, hv the imei number. theif has switched off the ph. so cant trac

Your service provider has the only chance of finding it so when yo reported it missing to protect your credit, they should have tried. The thief has probably removed the SIM card by now so you won't get through and even if you did, they might not want to tell you who they are. Your contacts might start receiving a lot of unwanted texts offering various services.