I had the exact same problem. Just got off the phone with MS.
The recent updates are now REQUIRING use of an email address for the user ID. I was using a member name for my user ID (and had been since the beginning of time). CM did a password reset for my account after he checked my account to see if the email adress was there. (It was). I used my same password for the reset, which was successful since it met the password requirements for length and numbers, etc). So now I will need to use my email address for all the Disney accounts.
I tried logging in to
MDE to make sure that worked (it was still working even when
DVC Member website wasn't). It was fine with the email address login, but it made me verify / update my account info.
I think I am good, now.
Did have to wait a bit to get a CM even though I called during the special website help period of 8 AM - 9 AM Eastern (5/19, 5/20, 5/21) - I think many of us were caught on the wrong side of this change.
Emilaylay93 - looks like you'll have to call, too.