How to get back my lost Iphone 4S?

How to get back my lost Iphone 4S?

These steps require that Find My iPhone was enabled on your device before it was lost or stolen.

Attempt to locate your device using Find My iPhone at icloud.com/find, or using the free Find My iPhone app.
Put the device in Lost Mode to set a 4-digit passcode and display a custom message with your phone number on your device. While the device is in Lost Mode, you can also keep track of changes to your device's location. Lost Mode requires that your missing device be using iOS 6 or later. If your device is using iOS 5, you can still lock your device remotely and display a message on the screen.
If you want to delete all of your personal information from your missing device, you can erase it remotely. Please note that when you erase a device, you will no longer be able to locate it.
Report your lost or stolen device to local law enforcement and your wireless carrier. Apple doesn't track or flag lost or stolen products, but you can use My Support Profile (supportprofile.apple.com) to find a list of serial numbers for products that you've purchased or registered with your Apple ID.
Note: If your missing device is offline, you can still put it in Lost Mode, lock it, or erase it. Your commands will take effect when the device comes back online.

If you turned on 'Find my iPhone' and have your Apple ID password, you can download the app 'Find my iPhone' on the App Store and you can disable your iPhone so no one can use it and you can also locate it, but the iCloud site may be more useful to do it that way.

Find my iphone if you have it on your phone

Track your phone using IMEI number.
It is very difficult to recover a lost iphone.
Recently one of friend lost his iphone 4s. We tried all the possible ways but couldn't find it