There are apps you can set up to track a phone but unfortunately you need to set them up on the phone while you still have it, so kind of a bit late if its already lost, sorry dude. If you happen to know someone in MI6 or who works for the tabloids I'm sure they'll be able to help track it )
If its an I phone you can download an app called Find I phone onto your pc. This will find your phone if it has enough charge and the phone doesn't need to have the app installed to do it. Worked for my wife's iPod touch, it was under the sofa.
