@Martin Sobel  - A bunch of questions to learn some more and hopefully spark some ideas:

• What plan type was this board created under? (Free, Team, Business, Consultant, Enterprise, Education?)
• How are you trying to access the board? Directly from a link or from your dashboard?
• When you sign to Miro and go to the team dashboard were you created the board, can you see it in dashboard/list of boards?
• If in your dashboard, it does for sure say that the owner is “me” as in you?:

  

   

• Are you still for sure a member on the team in which you created the board?
• When you try to access, I presume you are getting this message?

• 

• Do you have more than one Miro account and are perhaps trying to view the board from the wrong account? (see yellow highlighted text above)

Yes, you are right, I was answering your questions and I solve the problem haha.
What was happening is that I left the workspace where I created the boards.
I asked to the admin to transfer the ownership to me and then I recovered everything without any problem.
Thanks for the help!