I installed the myFTP plugin, to edit a js source file.
Without FTP, I couldn't see any of the site files, let along change anything.
I browsed down to the file I wanted, copied the text and backed out.
But when I went to re-upload the file, the path is the base URL and not the website URL. In the settings, it still shows the http://www.websitename.com for the website URL, images, etc.
I uninstalled the myFTP plugin - but all the posts relating to fixing this problem require me to access the files I could not get at in the first place, without myFTP.