Positive reinforcement, anonymous. If she has a favorite treat, grab a bag of them, sit on the floor, and offer one to her when she appears. Toss the treat to her and wait until she finishes, then present another treat to her. Don’t toss it until she crawls a little closer but hold it up and keep her attention as much as possible. Once she crawls even an inch towards you, toss her the next treat. Continue doing this until she’s close enough for you to touch. Feed her by hand at that point and pet her as gently as possible while apologizing for stepping on her tail. It’s important that you keep petting her gently until she finishes, as this will reestablish her connection to you and get her to consider trusting you again.
If she seems apprehensive whenever you enter a room after that, repeat these same steps. I would consider doing this with healthy treats or by alternating between treats and offering one of her favorite toys (hold it up, wait for her to crawl closer, and shake the toy in front of her again, rather than toss it to her) to avoid ending up with an overfed dedenne.
The Pokédex According to Bill 