Your question re: Fn key led me to the solution. changed to keyboard with F Lock key and I'm back in business.
Thanks for your help,
Steve

This is a Fellowes split keyboard and has no Fn key

forgot to mention that it is a wired USB keyboard

Thanks everyone for the greeting and generous advice. I am using the rear usb port, and the keyboard is usb2. Delete, F2, or any other key as it does not respond to the keyboard until after windows...

With Win10 on Dell 5150 there is no usb support at boot also no ps2 socket available therefore can't access startup or BIOS. Please help.
Thanks,