This happened to me this last weekend and I've been locked out of my account since. I've contacted SE via chat support but the say they can't unlink it via chat, only phone. That is the worst option for me since I live outside the US and calling is going cost me an eye. I tried to call today but had to give up since I was on hold for an hour. Can't wait to see my phone bill this month )=

Edit: And no, I didn't know there was an emergency code until I needed it. Guess it's part my fault for not paying attention.