HELP! Documents folder error message "Location is Unavailable" after installing Dropbox

I have been using Dropbox on the web and just installed it on my PC.  I did not intend to sync my entire Documents folder, but it never gave me an opportunity to select subfolders to sync within the Documents folder., and just started syncing. My documents folder contains a main subfolder, with many other folders and many files files within it (probably 3TB).  Dropbox is now syncing/uploading my docments folder with many days to go.   When I try to view that folder (so I can work), I get an error message that says "Location is not available" and I cannot see or access the hundreds of files in that folder.  How do I fix this and recover/gain access to my files?  I am concerned they are lost or that it will be several days before I can access them.