My iPhone was just stolen and when I open iCloud it no longer lists ANY of my phones, even old ones that I still have but my kids use as iPods. What is going on?
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.
May the iCloud Find my iPhone service doesn't work anymore because you have changed your Apple ID password and the iPhone (and the other devices you mentioned) can't login anymore into Find my iPhone. Try if it appears when you change the password back to the you entered in iCloud on your iPhone (and the other devices). I'd say that the iPhone (and the other devices) won't appear immediately, give it at least 3 hours, I don't know how often it tries to connect to iCloud if the password was wrong.