Adopted a cat a week ago. She has been hiding and wont eat or drink or use litter. What should I do?

Put her in a room by herself. Put her food, water, litter box, scratching post, and toys in there. That's so she can get used to the sounds and smells of your house. Visit as much as you want. When she asks to get out of that room and see the rest of the house, let her, but watch her. Don't go pick her up. Let her come to you.

Get rid of her.

Give it time . She or he is just scared . Be gentle and nice