Jira Board - I'm assigned as Admin and User, not showing up in Projects list

[JR]

I previously had access to a board and the original creator says I'm still listed as both an Admin and a User. The JIRA board has dissappeared from My Projects list and does not appear anywhere in my Dashboard. When I click links from my email that I previously received related to the board, it says the following message but as I have seen the original creator's screen showing my permissions, this cannot be correct:

This issue can't be viewed

The issue you're trying to view can't be displayed.
It may have been deleted or you don't have permission to view it right now.

[Nic Brough -Adaptavist-]

You need to check the permissions first - what exactly is the rule for "browse project" for the project?  If you match that rule (which I suspect you do not, as you say the project has vanished), then check the issue security scheme next.