My t-mobile razr has not had service for the past 2 1/2 hours or so. I'm in a place where I have always had service in the past, and now it is showing no bars and underneath it says unregistered where it normally would say t-mobile or whatever other service provider it's using. When I search for a network, it finds at&t and t-mobile but won't register for either one. What can i do?