Good afternoon.
First, check the connection status displayed by your watch. see this article.
Status icons and symbols on Apple Watch - Apple Support
If you could specify which of these icons appears on your Watchface or in you Control center it would be useful.
Check that your Bluetooth is On on your iPhone.
Restart both iPhones and Apple Watch. I know you tried this already but doing it once more before going further cannot hurt. http://help.apple.com/watch/#/apd521a8a902
Redo the pairing between iPhone and Apple Watch.
If you forgot your Apple Watch passcode - Apple Support This is also how to unpair.
Set up your Apple Watch - Apple Support
If all fail I suggest you take an appointment at the Genius bar.