Check he doesn't have an abscess from teething etc first. If nothing physical is wrong, then you need to take a completely different approach.
Some children simply aren't that hungry when you want them to be, so put back mealtimes a bit. Take the cue from him. Don't force food into him.
He is only 14 mths old! Meals don't have to be prepared specially, in fact if you put too much into the preparation each time, you're going to overreact if he rejects it.
At his age he does not need any 'snack' type food like junk, crisps etc, as it distorts the taste buds.
Keep it simple, nutritious and healthy. My babies liked feeding themselves so I would give them a platter of different things to try, eg slithers of cheese, raisins, peas, sausage, bread roll, orange segment, breakfast cereal flakes, sweetcorn, things that they could grasp, suck, play with etc.
As soon as they are bored, take the cue and take the food away.
(of course don't leave them just in case of choking), but it is a great way for them to enjoy the tastes, textures, feel of food. Mine did not like being fed with a spoon so this was a great alternative.
Let him chew on a peeled but uncut banana, give him a whole peeled apple to play with, lick etc, give him the spoon and some warm cottage pie and let him feed himself. Same with a pot or dollop of yogurt.
In short, keep it fun, varied, eat with him too, make funny faces, say yum! He'll copy you and the whole experience will be turned around.
Make sure he is hungry first and don't ruin his appetite with sweets/junk between meals as they can get surprisingly full.
Good luck!