cannot delete a folder ..tried many things..

I have a 1TB backup drive. I tried to delete a directory on that drive, but one folder
would not delete.

I tried rm -rf - failed
I tried to use rsync to delete it by syncing the directory with an empty directory.
No luck.

I booted up Windows 10 and tried several tricks there. No luck.
I cannot rename the directory.

Here is a sampling of the 2 main errors I get..
"the system cannot find the file or folder specified"
"the filename syntax is incorrect"

I checked : ls shows the file/folder. Thunar ( file manager) shows them too.
But Thunar reports that the whole directory and all the folders/files under it have size 0

I tried doing this with sudo - failed.

I've read many of the forum posts about this issue, and tried their solutions.

Any suggestions?