My dog used to eat from his bowl and all of a sudden he stopped

Has something changed with his bowl? Did you wash it and now it smells different? Is it even the same bowl? Has the food changed? -- different brand? Is it difficult for the dog to bend over to eat? Please give us more description.

Does he eat at all?

If he's refusing to eat it could be a tooth issue that's hurting him when he eats, could be a tummy issue that's making him refuse food. Could be so many medical things.

If he's still eating the normal amount he used to, but is just refusing the bowl, then refer to Wondergirls post.