@Paolo Platania 

You say:

I tried to connect via my email to my boards, but the system does not recognise my email. 

and then:

now I am excluded from my boards (I can see one that everyone has access to, but only as a viewer).

If I understand you correctly, you can still sign in to miro.com and have an account profile, but you can no longer see some boards you were able to see before.

Here is a post were I replied to a similar sounding situation recently. Perhaps it will help explain what could have happened:

https://community.miro.com/ask-the-community-45/lost-my-board-free-plan-no-link-11907?postid=46507#post46507

Hi @Robert Johnson thanks a lot for your reply. 

Basically I created the boards with my email and  now I can’t access to this boards with the same email. I can log in but I don’t have any board on my profile and when I try to access to my old boards I’m blocked.

Following your link It could be that someone of my team excluded me, but only two persons had the access to my boards and they don’t have the access too, now :(

If your previous team where the boards resided in – and the other two persons were members of that team – was a Free Plan team, then it sounds like someone in that team with the role of Team Admin removed your all from the team (or they deleted the team altogether).

Ok, thank you. Make sense. I contacted the support. I hope they can help me. 
thanks again

Alright, I appreciate it. Make sense. I got in touch with the help. Hopefully they can assist me.