Do you have the phone with you, or are you actually trying to find a lost phone? If you have the phone, go to Settings>Find My Phone. Does it say it's connected? If not, go into that menu and activate the service.
Hi schhjay. Were you able to get the Find My Phone to work using the suggestion from SydneyK? If you have your phone with you, are you able to access the internet and place/receive calls ok? There's also lots of great tips at http://bit.ly/V56EBR from Microsoft on this great service they offer.
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