When you can upload photos it will be helpful. In the meantime, try offering some baby food via plastic syringe or dropper. Just put some on his nose and see if he'll lick it up at first. I've had good luck with squash, green bean, and sweet potato baby food. If you can get your hands on some Oxbow Critical Care it is good to offer as well. This will help hydrate him and give him some nutrition. I also suggest weighing him regularly and recording the readings so you can track his progress.
If it's warm where you are, take him outside for some natural sunlight. Otherwise, he will need to rely on well tuned artificial lighting. If you can provide photos of his enclosure and details about it and his lighting as well, it will be helpful.