Ask her to back. Little pressure, wiggle the rope, wiggle the rope harder, smack her in the chest with it, keep doing it harder each time till she moves. Possibly use a short whip. Usually works sometimes gotta do it pretty hard.
My gelding doesn't like to stop pretty often. I'll get him to stop, if he tries to go forward a I back him about 6 steps, he caught on so usually he will just stand.
I agree with above, though needs ground work.
If put her in the round pen, work her, ask her to whoa, if she doesn't I'll then push them harder. Then after they seem kind of tired I'll ask again, to whoa. Usually by then they are tired and will do it. But eventually they just whoa when I tell them, cause its that or harder work.