my dog will not eat i tried to give him several things but still and he is laying down all day and doent want to do anything and yesterday he vomited yellow and today he has vomited like four times if any one knows whats wrong please anwer back i will very apreciate it.

Think you ought to go and see your vet!   Sorry not to be any more helpful - but without knowing any more about what your dog normally eats or what he does, its dangerous to rely upon an internet forum for advice of this sort.

If you are worried, see your vet.

Take him to see your vet. Not only is it illegal for an unnqualified person to diagnose illness, there's no way even a qualified vet could diagnose without seeing the animal.

I quite agree he needs to go to a vet PDQ

I am in complete agreement with everyone else.  Your boy needs to be seen by a vet, sooner rather than later!!