I am certainly no expert as I've only had Fluffy since xmas, but when we first got him, we put him in our ensuite bathroom to begin with. It was warm and quiet up there, with nowhere he could get stuck etc. We put his food, water, litter tray & bed in there and went in to visit him at regular intervals. After a day or so he got a bit braver and we would take him into the living room for a while (he used to hide behing the sofa etc to begin with), and we would return him to the ensuite when he'd had enough.

Over a week or so he gradually became braver and braver and started to explore different bits of the house, but we supervised him closely. We started letting him come into our bedroom at night too because he liked the company.

I'm sure she'll come round eventually but it'll probably take some gentle encouragement. Make sure she's got somewhere quiet and secure where she feels safe to go when she needs a rest!