Sometimes there are hidden files in folders that your server is not allowing FTP to see or remove. This has happened to me when I have made a bad test on my hosted site and created a .svn
folder.
I knew it was there but could not remove it. I had to ask my hosting provider to clean out the folder for me.
The re-direct is probably due to a .htaccess
file. (And maybe that file would not be shown, files starting with periods are often hidden.)
Probably your best bet is to ask your provider to clean out the folders for you and hopefully that will make things good again.