Here are a few steps to help you out If your iPhone or iPad has been lost or stolen.

Find my iPhone: What to do when your iPhone or iPad is lost or stolen
Check your iPhone’s location
If you had Find my iPhone enabled on your device, go to iCloud.com, click on Find My iPhone and you should see a map with all your iOS devices. Select the lost device, and keep tracking its location.
Turn on lost mode
To put your device in Lost Mode from the iCloud interface. Click on the dot representing your device on the map, and click on Lost Mode icon:
With Lost Mode, you can: