A few things to hopefully help.
1. If you could post about his living conditions, this will be infinately helpfull in getting an accurate response. What size enclosure is he in? How is it heated? what are the temperatures (highs and lows)? How old is he? How long have you had him? How long has he been showing this disinterest in food? Is he still pooping regularly? What substrate is he on? Has anything changed in his environment recently?
Without knowing this information it is difficult to guess what might be wrong, but i will try and give you some pointers and tips to help get him eating. The most important thing to keep in mind is that anorexia in reptiles is never a disease, buit a symptom. It can be a symptom of an illness, a parasite or such, or a reaction to improper environmental factors. I would get your leo, and a fecal sample to a herp vet immediately. it is important to rule out anything internal. If his health checks out ok, then its time to look at the husbandry and see if there are any errors there, thats why all the above information is important.
Of course, its most important we get this little guy eating, so here are some tips for that.
1. Im not sure what the apples were for, but leopard geckos are carnivorous. So they dont need any vegetable matter, or fruit.
2. Try varying the diet, crickets can get real boring after awhile. try some soft worms such as butter, silk, or wax worms. (wax worms are awesome for fattening up lizards)You can also try live pinky mice.
3.If the leo will not eat the worms on his own, try squeezing some of the guts onto him nose and let him lick it off, then maybe he will eat.
4. If he still wont touch these food items, you can try a product by flukers called "Repti-aid" get the one for carnivorous lizards and mix it according to the directions. Dab some on your lizards nose and he should lick it off. If nothing else, this should hold him over until you can get him to the vet.
Also, it would be really helpfull if you could post pics of the little guy, they didn't show up when i read your posts. My computer might be messed up, im not sure. But it helps immensly to see pictures.
Keep posting! I hope everything is ok.
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