I have had that issue about every 2 years or so for the past 6 years... all of a sudden my password is no longer valid. I have had no success getting into the acccounts, even using MS's account recovery form - I honestly think they ignore those requests. I have a Hotmail account, I've had to create a new one each time, but I rarely use it anymore for just that reason.
Yep, that's the one I attempted to use (unsuccessfully) each time... never even got a response... sent the form in at least three different times each time it's happened. I really do think they ignore it.