Hi Paul,
here are different sites where you can find help:
https://help.miro.com/hc/en-us/articles/360017572614-How-to-Restore-a-Deleted-Board
https://help.miro.com/hc/en-us/articles/360017572774-Board-Backup
So it is always good to save your board - I reccomend to save it every 2 or 3 days.
When you cannot find any solution maybe it helps to contact: support@miro.com
Michael
Thanks for the incredibly fast answer. Good news, I just logged in using a different browser and it shows again. Logged out and logged back in using Opera browser - still nothing is shown. So it turns out it wasn’t that the board got wiped as a problem with the Opera browser. Opera was working last week (its how I created the board), so not sure what changed.
Anyway, thanks again, at least I am getting by on another browser so this went from a LEVEL 5 - OH NO! to, hmmm that’s weird and unfortunate but can be worked around.