You may need a vet. our leopard gecko stopped eating too. For 6 weeks ( now 7)! We took him to an exoctic pet vet and now he's on all types of meds and hopefully on the mend. The vet said that 95% of gecko problems have to do with "husbandry." (cage set up) She had us make all kinds of changes and it looks like our situation may go on for a while. She gave us (we paid for it) a powdered food that we mix with water and give it to him with a syringe.

On the other hand, our gecko has been known to not eat for a while and kicks back in. But not this long. He's much thinner now and his tail is about 1/2 inch thick. That's about 1/2 the size it was.

Good luck!