It takes time, and your problems sound multi factorial with loss of appetite, feeling depressed about not eating, pain, the swallowing problems, and other matters have to be dealt with to eat, and enjoy eating once again.
As far as appetite, there are ways to increase that. Prescription Marinol. Megace, caffeine, wine, smelling of food, fat, and sugar. I watched the food channel even when I couldn't eat, which made me hungry, and so does the appearance of the food matter, room ambience, even the room color.
Saliva also involves taste, so increasing that will help with taste, and swallowing. Drink lemon water before meals, chewin gum, smelling lemons, hard citric candy, milk also replicates saliva, and coats the mouth, vegetable or any other healthy oil coats the mouth, and helps prevent mouth dryness.
The pain can be controlled by meds, magic mouthwash rinses, proper oral care, taking care of any infections.
For depression see about counseling, a support group, and does have factor in with eating disorders, such as self induced anorexia.
As far as foods, avoid hot foods, and serve warm, spicy, acidic, crunchy, which not only dulls the taste buds, but may also cause mouth ulcers or worsen them.
As Cheyrl mentioned, eat foods that easier to eat, and work your way up. I started taking pictures of my first meals, post treatment, and haven stopped since. I probably have a 1,000. I think my first bite was cream of wheat, with butter, sugar, milk, then added canned peaches, chicken broth with pastina, Chinese egg drop, soft boiled egg, and kept moving up the food chain. I eat everything now, from bagels to steak, pizza. You name it, I probably ate it, and make most of my foods. Prepared foods, frozen type junk, food coloring, badically cheap food taste worst than they did before, but do like an occasional Big Mac, fries.
My mouth tires out after a while in both chewing, and swallowing, so I eat smaller portions with plrnty of water. They say eating six times a day is better, but I'm lucky to do three.
One thing you can do is visit a buffet, and take a sample of everything, and see what you can tolerate. It beats making a whole meal, and not eating it, which I've done before, and right into the garbage, cause I don't like saving food depending how long it sat, and if I didn't like it the first time, I won't the 2nd time.
Even now, most proteins I eat are fatty cuts, not lean. I use sauces, make casseroles, fry, use butter, olive oil, so my foods are moist. There is a spray bottle, called, Misto, that you can put any oil in it, pump it, and spay on food. This will not only help swallowing, but the fat increases taste, appetite.
Some fight after treatments have a smell, and taste aversion to foods. Some which were probably associated with illness, nausea, vomiting. Proteins have a higher taste aversion that carbohydrates, which were easier to eat.
You want the softest scrabbled eggs, do them for 30 minutes, I actually do 20, and cook in a sauce pan, on the lowest setting, scrabble eggs 18 beats, and use 2 Tps of butter for every egg, a little at a time, and constantly mix slowly. Their so easy to swallow. I have others recipes, and basically live to eat. Today I made homemade macaroni, and potato salad, and going to have a cheeseburger with it, which i liked rare or med rare, otherwise I have swallowing difficulty, and toast, butter the hamburger roll, mayo, maybe mustard, ketchup. This morning I had eggs, fried sith bsvon, slice of butered toast. I know what I can eat, and don't think twice about it.
Tasting also involves more than just eating. It involves smell of food, hearing it cooking, seeing a nicely prepared dish, tasting with the 5 taste buds, and texture of the food.
Good luck.
