African Grey Parrot unusually inactive

Question
our parrot was in a good mood since the day we got him, moving about, eating, etc. suddenly the next day he was extremely quiet and inacive. he refused to be touched and reacts like he has never seen us before. I am concerned about my parrot and i am wondering whether it is sick, cold, hungry, etc.

Answer
-- How old is your bird ?   How long have you had him?  Are you positive it's a male?

Whatever additional info you can provide will be helpful.  Tell me what you feed him too, how long he spends out of the cage, whatever you can think of

Thank you