does anybody know what is happening? Shadows just do not work
No shadows whatsoever? Is this a new behavior or has it never worked for you? Did you check the position of the Light and Dark sliders in the shadows window? Have you checked OpenGL setting in Preferences? Specifically try changing Use Hardware Acceleration.
There are two broad categories of possible reasons for your issue: it’s either a hardware problem or you’re doing it wrong. You have provided scant little information to determine which it is.
I do notice from your profile, though, that you are using an on-board Intel GPU, which are notorious for their poor OpenGL support, so this is a likely culprit.
Thanks, it is working now