On my 2911 DK 45 cab, The pto and 4x4 on the kioti tractors , if they use the switch instead of a lever, have a relay under steering wheel plastic cover. You also need to test the output on the switch. I recall a few other people that had switches fail. Theres also a 4x4 solenoid under the tractor, but i hope thats not the isdue, cause thats very expensive.
The pto and 4x4 use the same fuse, so if pto is working, its not the fuse. There is a wire running to the 4x4 solenoid which may have been damaged.