False file permission denied error when opening one specific word document on my Mac
The permissions look okay.  Maybe you're not (or are no longer) the owner.  Try opening Terminal.app  Then type: chown USER ~/Desktop/FILE replacing USER with your username, and FILE with the filename plus the extension, assuming it's on your Desktop.  If you've executed the command successfully, it will seem like nothing has happened.  If you fail, it will complain, but you're not going to harm anything. 

Then try to open it.  

Aside from that, I'd maybe you could have encrypted it by mistake?