my iphone stolen! i want to block it and will not work when they open it
Block this iPhone.
iPhone 6, iOS 12
Question marked as
Use the Find My app on another iPhone, iPad, Mac or https://www.icloud.com. On your iPhone or iPad or Mac, open Find My, scroll to your device name, tap or click it, and then click 'Activate, which is located under the 'Mark As Lost' title. As soon as your phone connects to an internet connection, whether cellular or Wi-Fi, it should then become a useless device to them, thanks to the secure enclave. See Use Lost Mode in Find My iPhone on iCloud.com - Apple Support.