My adopted cat wont do anything?

I just adopted a cat and he is 3 years old and has been in the shelter for two years i have had him for about a week now and he wont really eat or get out of his bed and he crys and crys for hours when im not home and my dad is there but when i come home he is usually normal but he wont ever just get up and sit next to me or lay with me he is very distant i dont know what i should do .