Currently Being ModeratedNov 13, 2013 11:48 AM (in response to AlfredJB09)
If it is off then you can't use the web to locate it. The only alternative is to start looking for it like anything else you have ever lost.
If you activated Find My iPhone and seeing as how it is running iOS 7 that activates Activation Lock which means that it can't be used by anyone that doesn't know your Apple ID and password. So it will be a brick for them and totally worthless.
You should report it to the police and your carrier. The police will not be able to find it by the serial number.
Currently Being ModeratedNov 13, 2013 11:52 AM (in response to AlfredJB09)
The only way to find a lost iOS device is to use the Find my iPhone app or www.icloud.com. For this to work, you have to enable this feature (Settings > iCloud) on the lost device prior to loss. If you didn't do this, there is no way to find it. Also, if the device is turned off, there's no way to find it. Neither Apple nor your carrier will find it for you.
Setup Find my iPhone:
Here's a good tip from Kappy on what to do if you device is lost or stolen:
Currently Being ModeratedNov 13, 2013 12:54 PM (in response to AlfredJB09)
Allan is correct; if you set up Find My iPhone in iOS 7, then even if the iPhone is erased the thief still can't use it without having your Apple ID and password. If anyone's found a way to crack Activation Lock yet, it hasn't been reported in any of the media that I've seen, though of course no system can be absolutely foolproof.