My iphone was stolen how can I retrieve it

First, Find My must have been enabled before it was stolen. It needs to be powered on and connected to a network. If all three are true, you 'MAY' be able to track it. But most stolen phones are never recovered. Thieves usually put a stolen phone in a Faraday Bag, which blocks it from communicating with networks.

See that you can do here --> Find your lost iPhone or iPad - Apple Support

Please Note: Apple doesn't get involved in lost or stolen devices. If you get a message purporting to be from Apple saying your phone has been found and asking you to validate with your credentials, it is NOT from Apple, but the thieves, hoping you'll give up your credentials, so they can wipe the phone. Don't fall for any messages even threatening messages.

Next, call your carrier and ask them to Blacklist the phone so it can't be activated on any networks.

And finally, be prepared to buy a new phone. Most stolen devices are never recovered.

Hello~ Click on below…

Find your lost iPhone or iPad - Apple Support

~Katana-San~

First, you need to locate the phone to be able to possibly retrieve it.

Find your lost iPhone or iPad - Apple Support

But, don't try to retrieve the phone yourself if you are able to see its location.