OK, after deleting the AH-64D folders for the input configuration, they are working again. Something strange in the config was changed.
And now I have to assign all buttons for 3 Virpil Panels, the throttle and the stick again. How lucky it is Sunday...
EDIT: I have deleted those folders:
C:\Users\[...]\Saved Games\DCS.openbeta\Config\Input\AH-64D_BLK_II_AI_Menu
C:\Users\[...]\Saved Games\DCS.openbeta\Config\Input\AH-64D_BLK_II_CPG
C:\Users\[...]\Saved Games\DCS.openbeta\Config\Input\AH-64D_BLK_II_PLT
Nereid's post in Power Levers not working with Axis anymore? was marked as the answer