It's not funny I am worried about him and he vary young only 6 month old. And he big rooster . Green watery stool not walking much just laying down he still eats and drink he has no worms
How is my response coming off as a joke? Literally anything can cause lethargy and it would be irresponsible to go buy a random medication and dose him. The questions are there for a specific reason and in all the the time you've taken to respond to these messages you could have just sat down and answered the questions.
We need to know how long he's been sick, if you can observe any physical changes, any changes in the comb, facial swelling respiration (Breathing), paleness any signs of trauma, has he been eating, is his crop full, soft, squishy, swollen, what kind of feed he gets, does he free range, what kind of housing does he have. Pictures are very helpful, even pictures of his stools. Have you inspected him for lice or mites?
Common causes of lethargy are: anemia from mites, not eating (could be an internal problem effecting appetite), internal parasite overload, or some sort of respiratory problem. All of those would require a different treatment.
And in the mean time if you can isolate him for observation that is helpful and can potentially protect the rest of your flock from getting sick.