What do I do if my 2000 honda passport gets somehow stuck on 4wd setting?

What do I do if my 2000 honda passport gets somehow stuck on 4wd setting?

It has low fuel

You first check to make sure all the tires are the exact same size. Mixed sized tires will still go into 4WD but it won't go back to 2WD on pretty much any make 4WD vehicle.
You cna also try putting it in 4WL and in a parking lot do gigure *'s in both directions. Try shifting from 4WL to 4WHI a half dozen times and the see if you can get back into 2WD. There are solenoid switches that stick if you only use 4WD once or twice a year and these procedures may help get oil on them and loosen them up. If that doesn't work the dealer has the factory scan tool that can read transfer case switch codes and monitor them to see if they are working properly.