The Dropbox desktop app on Mac lost file content and isn't syncing

Walter​ - thank you for the responses. 

Here is a screenshot from my computer. All files show icons of the app (Acrobat icon for PDF, etc) but no file or image content and list zero bytes for file size. 

I have quit/relaunched everything and that doesn't make a difference. 

I'll try rebooting and the directions to copy outside the folder and move back

NOTE: When I had to re-download the Dropbox app it was trying to add a new Dropbox folder onto my computer. It gave no information about my files already ON Dropbox (where they are or how they'll be saved/synced) and it logged me into a secondary account instead of the primary one with all my files (which I did log into the primary one but then saw it displayed a different email address in the dropdown of the menu bar). I did get it logged into the primary account and it seems to have all my files, it's just not synced and the content isn't there when I want to access files on my computer the same way I have for a decade or more.