Well problem solved. I re installed the program and there was an option to add it to the menu when you right click on a file. "Open With.." still won't work but that's ok because there is now another option to open with sublime text that is separate.
And my FTP program had a separate sorta hidden configuration option to manually select the editor program to edit files on the remote server. So even though sublime text still no longer shows up under the default list programs to edit files with alongside notepad and wordpad etc, I can still open files in sublime text by setting the ftp program to use it every time. Which is handy for times like today when I wanted to make a bunch of css and markup changes on the server without having do download/re-upload etc or use a different editor.
So while it was nice, and a little nostalgic to get re-acquainted with notepad++ again today, I'm back to using sublime text. Yay!