my two yr old will sleep in her bed but will not sleep through the night. and if she is not sleeping when we put her in there she will not stay in there.
One or two nights of you staying up and putting her back in her bed every time she gets out ought to cure her. It'll be hard, tiring, and emotionally draining for both of you, but it'll probably work. A friend of mine threatened her daughter with a spanking even after she kept climbing out of her bed, and the little girl said, 'ok, but then can I go to bed with you?' SO that didn't work, lol... Try and try again, be consistent with her. I don't think it would kill her (or you) if you even slept on her floor for ONE night. She is eventually going to get tired and fall asleep. Good luck with it. :)
don't give them a choice, keep putting her back as long as it takes. Once she learns you make the choices and not her, she will stay there. Just don't give up.