If you have lost an iPhone, then don't be disheartened already. You can find it using its built-in feature called Find My App. It will help you check the location of your missing iPhone, permanently delete data and even mark your phone as lost. This feature is automatically enabled, so if your iPhone is stolen or lost, you will most likely be able to track it down and secure your data. To find your device, you'll need to sign in to iCloud.com/find or use the Find My app on another Apple device that you own. If your iPhone doesn’t appear in the list of devices, then Find My was not turned on. But, you can still protect your account by changing the password for Apple ID and social media accounts such as Facebook, Twitter, Snapchat, among others. You can also choose to mark your device as lost and remotely lock it with a passcode to keep your personal information safe. This also disables Apple Pay on the missing device. And, you can display a custom message with your contact information on the missing device. Lastly, you can erase data on your iPhone remotely. But, once you delete your information, you won't be able to track your lost iPhone's location, so make sure that you no longer need to search for the device. If you have AppleCare+ with Theft and Loss, then it is recommended to avoid erasing your iPhone until your claim has been approved.