I'm bit confused. "Access denied" sounds like you cannot even connect (authenticate). Yet you wrote that you get "/ <root>", what looks like you can connect. Or do you get "Access denied", when you try to browse to a subdirectory? A log file or a screenshot might clarify that.

In any case. Either something has changed on the server. For that you will have to contact your server administrator.

Or maybe you have browsed out of the folders, where you normally work, to a folder, from which you cannot go back easily, because your work folders are hidden. Try pressing the "Home" toolbar button to get you back. If that does not work, try clearing the initial Remote directory on the login dialog, to make WinSCP default to the "home".

I have been using WinSCP for several years with no problems. But a few days ago I must have made a mistake because now I cannot use it at all, I am logged in but cannot do anything.I have /<root> and I don't know what to do.
Anne-Marie