Windows 7 desktop hidden ( strange )

I am using Windows 7 for a long time but yesterday something strange happened with me.
When I switched on my PC, all folders on the desktop were hidden.
I have no access to folders, even when if I copy some new folder to the desktop it disappears and is not shown on the desktop but when I go to run and search for desktop, it opens as a folder in front of me and I have access to all files and folders. I hope to get a solution here.
All settings are ok!

