To find a lost iPhone, go to iCloud.com, log in with your Apple ID credentials, click Find My iPhone, and then select the missing iPhone to begin tracking its current location. If the missing iPhone is switched on, its current location appears on the map.
If the map shows that the lost iPhone is within your reach but you cannot find its exact location, click the information window of the device, and then click Play Sound. This plays a loud sound to help you find its exact location. If the map shows that the iPhone is not within your reach, click Lost Mode on the information window to lock the device, and then create a custom message with your contact details to anyone who picks it up. For this process to work, you must have enabled Find My iPhone on the lost device before misplacing it.
Alternatively, if you have enabled location history and reporting on the lost iPhone, go to the Location History page of Google Maps, select the current date on the calendar, and then check the map to view the last reported location of the missing iPhone. On the left-hand side of the screen, check the last time the lost iPhone sent a signal to Google Maps.