Desktop icons locked - no drag & drop anymore

I cannot move my icons freely over the desktop anymore.
When I try to move any of them, it comes back to its previous location.
The "line-up" icons desktop menu worked: It lined up my icons but I still con't move them.
Also, when I try to drag & drop a file into a folder , it does not work: the files comes back to its previous location.
The drag & drop does not work either in an Explorer window.

Any experienced user that could help me ??

Thanks

 

Right-click on an empty spot on the desktop.

Go into "Arrange Icons ".

Uncheck the "auto arrange" thing at the bottom.