If your device has been stolen or lost, here are some steps to take:

1. Immediately contact the police and report the theft or loss.
2. Change your device password or PIN to ensure no one other than you can access it.
3. Check to see if your mobile device has a location service that can be used to locate it.
4. Contact your cellular provider and inform them that the device has been lost or stolen and have them suspend your account.
5. Notify the relevant app providers or software vendors and update the account information stored on the device.