So, a lot has changed, and new accounts were created for everyone. Sadly, that means- new passwords.
The easiest way to do things is to reset your account. (Provided the emails have been reactivated by now).
Alternatively, using your email address to log in, and your old username (as opposed to the Display Name which was shown to everyone else) will also get you in.
And if you have any problems, feel free to email/message me!