My truck is stuck in 4wd but it there's a burning smell coming from that box that's on the passengerside behind the kick panel. Wjat is that box called an what does it control. My fan motor want wrk an my horn either sense this smell. It's a 98 chevy blazer 4wd

Not sure what kind of smell you got but your heater core is behind there as well. Easy to fix.

Remove fuse #15, 10A and see if 4x4 disengages. Your truck has a Transfer Case Control Module that may be what's behind the kick panel. As for the horn and fans not working I can't see a direct electrical connection between them.