Can I ask where did she come from? Perhaps she hasn't been exposed to the outdoors and she's experiencing fear. Some dogs tend to freeze or 'shut down' when they are overwhelmed and frightened.
Does she have any favorite treats? I mean the yummiest stuff she wouldn't turn down (cooked beef, chicken, dried liver)? You're going to have to observe her carefully and each time she looks at a person, car, etc., you can say "yes, good girl" and treat her. Your goal will be to teach her to associate everything new in her environment with positive outcomes.
Rather than forcing her to walk, I think you should start real slow and just hang out outside with her, in her comfort zone. If you notice her take a step, yes, even a single step, in any direction other than the front door, reward and praise her.
It'll take some time so be patient, talk in low, soft tones (not high-pitched), and let her show you when she's ready.
Would you have any pics of her to share
? And what's her name?