skydrive files gone

I was working on a spreadsheet today, one I've been working with for several years.  It is a shared file we use daily for several years.  We are experienced users with skydrive.  I shut down my pc, and upon firing things up a couple hours later, all of my files and folders are gone from Skydrive.  There is nothing in a recycle bin.  We did not delete any files, certainly not all of our folders.  We use the web interface, no apps or syncing.  What's up?