Trello messed up my account by binding a new one into it by forcing me to use Atlassian Account

[a b]

Hello

As the title says, I was happy with my trello account.
Today, I logged in after some time and it forced me to do an atlassian account.

My username changed from username1 to username3, so apparently it binded  a new user to my account.
All boards disappeared, unaccessible, tied to the old account. I cannot figure out how to get to the back username and I tried to change it manually in the browser but to no avail.

How to get my old account?
I already contacted support but they are slow in responding. So I'm in a middle of a project with all trello boards and cards unaccessible by me (the admin) but can be accessed from my team.

Nice

[Nic Brough -Adaptavist-]

So instead of setting up an Atlassian account based on the old user name, you chose to create a new one.  That's fine, but it does mean Trello now sees you as two separate accounts.

You'll need to get the old account set up as an Atlassian account and give it full permissions, or get everything  transferred to the new one.  Then you'll need to think about which account you're going to use going forward and probably get the other one shut down.  

Trello support can help you "merge" these accounts if you need to.  Contact them on https://trello.com/contact#/

[a b]

It happens that microsoft (whome I have mail with) has a subdomain or something and I was mistaking it with the right one.

Basically they have microsoft.com and onmicrosoft.com and I was with one of the two and tried to log in with the other.