My Siri stopped working for me a couple of months ago as I was meeting a friend at a mall that has an Apple Store. Never even saw a Genius, the greeter looked at my phone and saw a game program was messing up and making lots of code, she erased something in diagnostics, we rebooted and Siri came to life. I do not know more than that but if that doesn't give you enough clues to remedy it, then I hope you can run into an Apple Store.