escape and function keys not working

Hi,

I have got a Latitude E7440 with Win10, and the escape and function keys stopped working for a while. I tried all the online suggestions I could google out.
The list of suggestions I tried so far:
1, uninstall/reinstall keyboard drivers
2, change bios settings (no settings available for Fn keys in A20 BIOS version anymore)
3, update all drivers including chipset drivers
4, in Win. Mobility Center there is no Dell extension, so Fn key settings are missing from here as well
5, shift+esc is also not working

What's next?