Desktop, OneDrive, Box files have disappeared from MacBook -- yet the folders remain! How do I find the file contents?

Recently I went to my OneDrive on my 2014 MacBook Pro to get some docs, and ALL the folders were empty. (OneDrive is formerly SkyDrive.) I also use BOX. I checked the trash bins on my Mac and my OneDrive. Nothing. Then I realized that ALL my folders were empty -- including those on my desktop and in BOX. ALL my work is gone. This is a big deal...and unfortunately, I did not use Time Machine.

The whole idea of the external drive was to protect these docs. They sync with the computer -- if the computer docs disappear, so do the contents on the external drives. But regardless, anything that was IN A FOLDER is gone -- xls, PDFs, docs, etc. iTunes and pics are okay.

About a week or so before this I downloaded Picasa. Not sure if this may have had an affect on my computer.

I contacted Microsoft and they are useless. I went to the Genius bar, and they never heard of such a thing. They have moved it up but haven't heard anything from Apple. This is something that happened due to the MacBook operating system, not a virus. I've seen other similar posts where files "just disappear" but not to this extent.

I really need some help or a forensic person to figure this out. It is quite problematic. I appreciate you help mucho....

THANKS!!!!