Re: Logitech keyboard K260
May not be anything you can do ...
Did the setup come with a small USB device that you plug into a USB port on your PC?
Did the setup also come with a driver CD?
If the answers are yes, this implies that, despite using a USB plug, the keyboard requires special drivers -- which you are NOT going to be able to install in Linux.
Sorry ... but I had the same problem with a fancy Logitech keyboard and had to ditch it for a simpler one that would work.
Ubuntu 14.04, Mint 17; MS Win 8.1.
Will not respond to PM requests for support -- use the forums.