404 page not found returned by only one project in server and this project's master branch is removed

Hi,
like title, only one project in my server returning 404 error.
So I can reach projects page, but I can’t access to my main project.
And master branch which I did not remove is missing.
This happened when I turn off server pc.

I tried reconfigure and restart gitlab (gitlab-ctl restart), but nothing changed.
How can I solve this problem?