Find My iPhone is the first downloadable app we have added to the iPhone hints and tips section. It is Free and is developed by Apple.
Apparently, Apple wants every iOS mobile device user to be able to find their lost or stolen unit, because Find My iPhone is now a free service, with the ability to log in to me.com using your Apple ID. Unfortunately, the free edition of Find My iPhone requires a current generation iOS device, which means, an iPhone 4, fourth-gen iPod touch or iPad.
The first step toward feeling secure that you can find a lost device is to head to iTunes (either on your computer or from the device itself) and download Find My iPhone.
Sign In With Your Apple ID

On your iPhone, go to Settings --> Mail, Contacts, Calendars--> Add Account and select MobileMe. Enter your Apple ID, which is the same as the one we use to shop at the iTunes store. Type it in and move to the Password field, enter that and tap on ‘Next’. Apple will verify your credentials and a screen will appear with your account and the text ‘Find My iPhone’ with a switch next to it. Flip the switch to ON, and tap ‘Allow’ at the prompt and then Save to activate.

Cannot Access Account Address. Review Account Information in Settings Fix
After setting up your new free MobileMe account, to take advantage of the new "Find My iPhone" feature you may start receiving a pop-up error message ‘Cannot access account address. Review account information in Settings.’
It appears that the free MobileMe account is attempting to check for a MobileMe e-mail. To stop these error messages go to Settings --> Mail, Contacts, Calendars --> Fetch New Data --> Advanced--> MobileMe and select ‘Manual’.
Exit out of Settings and you're done.
Registering More Than One Device
If you are lucky enough to own more than one Apple iOS device you will need to download the Find My iPhone app on each device. You will also need to, sign in with your Apple ID and make the Account Access fix on each device, as described above.
Launch Find My iPhone App
Launch the Find My iPhone app on your iPhone and enter your Apple ID and Password. After successfully logging in the app will start locating your iPhone. You will either be presented with a list of your iOS Devices that are activated and their status or a map showing where your device is located and how long ago it was located. In the list of devices screen, click on a device to be shown the map with its current location.

There are three map viewing options, Map, Satellite or Hybrid to select from. The map shows your device in the centre of the screen with a blue arrow indicator to the right of it. Click the arrow and you will be presented with another menu. From here you can:
Display Message or Play Sound – Select this option to either display a message on your iPhone screen or to play a sound. You can select both options if you want. If your iPhone is set to silent playing the sound activated through the Find My iPhone app will override this.
Remote Lock – This option remotely locks the iPhone. You can still display a message and play a sound if the iPhone is locked.
Remote Wipe – This option will wipe all of your data from the iPhone.

Launch Find My iPhone from PC or Mac.
From a PC or Mac visit me.com and enter your Apple ID and Password and click the ‘Sign In’ button.
After successfully logging in a map will display with a list of registered devices in the left hand side and the selected device shown in the centre of the map.
There are three map viewing options, Map, Satellite or Hybrid to select from. The device in the centre of the screen will show a blue arrow indicator to the right of it. Click the arrow and you will be presented with another menu. From here you can:
Display Message or Play Sound – Select this option to either display a message on your iPhone screen or to play a sound. You can select both options if you want. If your iPhone is set to silent playing a sound activated through the me.com web site will override this.
Remote Lock – This option remotely locks the iPhone. You can still display a message and play a sound if the iPhone is locked.
Remote Wipe – This option will wipe all of your data from the iPhone.
