My iPhone was stolen and now doesn't appear in iCloud?
You haven't mentioned it, but even if you had your location services disabled and your iPhone was untrackable with "Find my iPhone," you should inform Apple that your phone was stolen. If you bought your iPhone new, then Apple will have record of that iPhone's serial number (and probably MAC address) associated with your name. If the serial number shows up in their systems, either by the thief seeking support from Apple, or by the theif's creation of an AppleID and attempting to reassociate that iPhone to their name, Apple can flag the activity as suspicious, remotely wipe the phone, or more likely, simply disable it. I highly recommend calling Apple support and reporting that your iPhone was stolen.