A Microsoft file hosting and synchronization service.
Any other ideas how to contact MS as I have the same issue and really need to be able to access my personal vault, when I select the ? button for help I get "Use the search box to tell us what you're looking for or browse for content on the //Office help and training site."
A few weeks ago accessing the personal vault through File Explorer stopped working, the issue re the popup box disappearing after Step 1 of 14 and Stop box popped up saying "We couldn't unlock your personal vault" so I started using the OneDrive using Onedrive.com, and now this issue means I have no way of accessing my files I had saved in the vault.