Aww. Bless her. She will come round - Just spend quiet time sat on the floor in the room she is in, without trying to force her out of hiding. She will get accustomed to you and should start coming to see what you are doing! The main thing if she is nervous, is to avoid sudden loud noises or sudden movements near her, as this will reinforce her fears.
My boy spent the first weekend under the bed in the spare room, and when I went out and left him, I got home to a very vocal boy with 'hands on hips' on the stairs, demanding to know where I had been..... I have been under the paw from that moment on.