Sometimes when a snake doesn't take a meal it might indicate that there is something in the husbandry that isn't quite right. Have you checked your basic husbandry: hot and cool temps, ambient temps, humidity? How long have you had her and what is her age and weight? What type of enclosure are you using for her?
What I'm getting at is that the more information you share about the snake's environment, the better someone might be able to help you!