Same thing happened to me today. I logged in a few hours ago, setup my deck for a farm deck since I was in the T50 and logged out. Now I go to log in to play a bit, and am told wrong password. I thought, okay, maybe my password is wrong (after a few attempts), and went over to Kongregate where I started the account (don't need the password there). It tells me that the Username doesn't exist.
I'm assuming that my account has been deleted, but not only am I not sure why (or what happened), but on top of that, *IF* I were banned (and no idea why I would have been banned) , after looking thru the forum from people who have been banned, it appears it tells you that you were banned. So if this is happening to a few people in a short amount of time, I'm hoping that it's a database issue, and that it will be resolved soon.
Thanks.