I also use WS_FTP. Actually it's an old version - last time I tried to get the free one it wouldn't let me, but I digress...
I can understand why you don't get what you expect if your host has changed the file structure for your site, ie: the site is now in a different folder, but you should still see the correct files on your pc in the left pane.
Things I can think of trying....
You are connecting using the correct login right? You didn't manage to login using a different setup, which is pointing you at the wrong folders?
Try browsing for the folders you want from your pc in the left panel. Do you get anything at all?
Can you browse anything in the right pane? Can you go up/down etc?
Who is your host? Mine (POWWEB) a few months ago changed some settings and it could be that yours disabled ftp access to your folders or changed your ftp capabilities. Do you have a control panel for your host that you can log into? That might give you some answers about things they have changed, or they might have a forum where you can get answers also.
Let me know if this helps.
Good luck.
Yes it's frustrating isn't it.............
Tony