If you lost your device, we recommend using the Apple and Android services available to help you find the missing device. These services can also be used to lock the device so no one can use the device and/or delete all content from the device remotely. These services must be enabled before the device is lost in order to work properly.
Apple Devices
https://www.apple.com/icloud/find-my
Android Devices
https://www.google.com/android/find