New
#1
One partition suddenly inaccessible
1909
diskmgmt.msc also showed it to be healthy.
diskmgmt.msc's properties was the only thing that revealed that all permissions were gone!.
I was able to create ("Add") permissions in the properties' Security tap. Problem solved.
I am writing to ask whether anyone ever has encountered disappearance of all permissions
to a partition. I never had.