Teach her voice commands from the ground, or have someone lead her while you teach her to react to your leg pressure. Remember that riding is a gift. Horses dont have to allow us on their back, but we ride them anyway, so take things slowly and focus on the well-being and happiness of the horse.
Get off and work her tail. Lunge, lunge, lunge. Chase her with a plastic bag if that's what it takes to mover her feet. You really need to let her know that you're the boss, not her, and when you say something, you mean it.
I would also rule out any pain and tack fitting issues. Do you work under an instructor?
The main thing is only using your legs when you are actually asking for something, and to be very definitive when you do. This doesn't mean having no contact on their sides, but being very explicit when you do ask for something. also remember to always reinforce your leg with seat, eyes, voice, and rein.
Also remember that you may have to use artificial aids, and that they aren't a really bad thing.
I almost always carry a crop when I ride, but I haven't had to use one in well over a month. Your horse needs to learn how to move off your leg again and this may take some artificial aids. As long as you use them properly, they will not injure your horse and will help you in the long run. Make sure that when you use your crop/spurs that you use them after having explicitly asked for something with your leg (and reinforced it with other natural aids), and that you do so definitively so that you don't end up using them excessively, which can take away their effectiveness, and injure your horse.