@Reni -

If you are on a paid account, you could find your deleted boards within the Recycle bin for each Team - they will be there for 30 days. You could then restore then from there.

If you are on a free account, you only option is to access the deleted boards using their individual unique URLs. When you do so, Miro would prompt you to recover them.

Kiron

And if you deleted all of the boards by means of deleting the team they were in, you will not be able to recover the boards.