There are many rasons that a corn will regurge so it would be impossible for anyone to tell you exactly why yours did. But some reasons could be: Handled too soon after eating - should always wait 48 hrs after eating before doing anything with them; Temps too low for snake to digest properly - if the snake cannot get warm enough, it cannot digest the food and will regurge it, otherwise it would rot in its stomach, make sure the warm side is warm enough (also make sure that itis not too warm); too large of a meal - make sure you never feed a larger item than the snake can comfortably eat, you should see a noticeable bulge but not a large one; food fed too often (which obviously is not in your case since you can't get them to eat); going too long without eating and getting a normal meal which would prove to be too much for the stomach to take; food fed too close to a regurge event - always wait 10 days after a regurge to try another feeding and then it should be only half the size food item as what they would normally get, so if it is a hatchling that regurges, a pinky head should be all it gets for its next 2-3 meals spaced 7 days apart, then you can go back to a regular sized meal item at regular intervals if it holds down these meals; a sick snake - one that was born with abnormalities or one that has acquired a sickness or parasites, obviously if it is because of parasited, a vet should be contacted for the proper medications; too much stress. There could be other reasons but these are the most obvious/comon ones. It is up to you to decide/figure out, what the cause COULD have been, we cannot tell you. Remember one thing, sometimes it is just not obvious for what reason it happens, it just happens. So, the important thing is to avoid, at all costs, a repeat regurge. A snake that regurges a few times in a row is not one that will likely make it. So, make sure all the above are checked/followed and then you will have done your best to help this guy along.
There are LOTS of ways to help get a non feeding snake to eat but I can't go into them right now. Anole feeding is one way if you can't get them to eat, but they get to like the anole and you have to switch them over by scenting the pink with an anole - usually done by killing the anole and rubbing the pink in the opened carcus, this gets the snake to eat the pink thinking it is an anole and you scent the pinks less and less with each feeding till it is eating an unscented pink. I have and am working with non feeders and this works very well. Yes, the snake COULD pick up parisites from the anoles but that is something you can clean out of your snake later. Eating some anoles is better than them starving to death, better a snake you have to deworm than a dead one. But there are many other ways including tease feeding, force feeding (either adult mouse tails or pink heads), putting into paper bag with pink, braining pink, etc. etc.
Good luck with you little ones and watch that regurge one, make sure it stays warm.