Lost all sprints and backlog

Question

I'm using an on-demand Jira & GreenHopper at https://dataprj.atlassian.net, I have an agile board and backlog with all unresolved issues, but after few days with no update, today when I come back, all sprints have accidently disappeared, the board & issues still remain but backlog is empty.

In some issues I can see the sprint which it belongs to, but can't open sprint as it notices "There are no boards which contain this sprint.".

Is it caused by the recent update or maintenance, how can I restore the backlog & sprints?

DoK · Answer

of course, I logged in, and I have the administrator role on that site

You can open some recent updated issues from activity stream, which still have the Active Sprint field (in the bottom-right 'Agile' section), but can't open the sprint.

Penny Wyatt (On Leave to July 2021) · Answer

I notice that the issues on that instance are anonymously accessible. Are you sure you're logged in?