Is the nose dry because she's lethargic? Whether or not a dog's nose is dry really has nothing to do with their health unless it's dry because they are inactive because they are feeling ill (which is probably how the myth came about since a sick dog might not be too active). How long has she been not eating? 24 hours or any other signs like lethargy, depression, vomiting, diarrhea, fever, obvious pain, shaking, white or pale gums, change in behavior or drinking (more than normal or less than normal anything abnormal) anything different or not normal at all and I'd see my vet sooner. If there's no other signs and she doesn't eat for 24 hours you need to see the vet as there is likely a physical cause. You should watch for hypoglycemia as well especially if very small or a history.
If your dogs nose isn't wet then that means he is sick and should see a doctor.he isn't eating maybe because he dose not like that kind of food so you should probably try variety of different food and a you should by it some snacks and treats.
She id dying
I would take her to the vet
If its dry its sick go call the doctor
She might have a digestive problem, or he or she could have something wrong with his or her teeth.