Volume keys are at once arrow keys?

On my HP notebook, I can suddenly no longer control the volume with the appropriate keys but must go with the mouse on the volume icon and regulate it. What can I do to get my volume buttons back? If I now press the keys that act as left and right arrow keys. Is an HP with Win 10.

The Fn-key is still working, that must also press?

other things work with Fn?

if not, then update the driver for Fn…

Thank you very much