I happen to agree 100% with Shannon. Kittens need time to adjust --they are small and need a world small enough not to ne overwhelmed, by noise, other animals, people traffic etc--Confinement to one room with all her needs food, water, litter box she will eventually come around and wander out one day--so leave the door ajar.
Bet it would not hurt to get a feather and play around on the floor with her/him, either?
Shannon writes some very good advice.
To a small young kitty, being put into a new habitat, without all she knew (Mama and her sibs) is very intimidating.
Quiet, persistent kindness is the key.
If she is using the litter box, you can be assured she is eating and drinking.
Sit down on the floor of her room and do not try to get her to come to you. Her curiosity will overcome her shyness as she learns that you are someone she can trust and rely upon to fulfill what Mama used to provide.
Make sure you start off by only letting your kitten be in a small room so that she feels comfortable. You can then slowly give her more freedom when she feels ready. I would leave the food in the room with her and close the door; let her come out when she feels comfortable and safe. Try and keep a quiet environment around her. You may even start her off in the bathroom so that she feels safe in a small room, but she is out so that you can sit and pet her and talk to her. Try to entice her to eat with you sitting there and make sure and pet her while she's eating to make her feel comfortable with that. I am dealing with the same thing at the moment and my little guy has learned to associate the bathroom with food and runs there when he sees me now. The biggest thing is to be patient and give your kitten plenty of places to hide and make sure the litterbox is in a safe place (low traffic area, not accessible dogs).