Quote: Unfortunately you don't know what is wrong so we can't make any further suggestions.
Perhaps if you described it a bit more it can help us figure out what it is and we can go from there. Does she stand upright but just refuse to put one foot down? Is the foot sticking out at a weird angle or is it under her in the normal position? Are her toes flat or are they curled? Does she walk with a bump or does she hop on one leg? Does she ever put the foot down for stability? How old is she? Have you looked at Mareks Disease and the symptoms from that?
I have one girl right now that looks like she sprained her "knee" and is wobbling around with her leg at a weird angle - so I know they tolerate extreme pain that would put us down in bed for a week. We have also had a young pullet that got jumped on by a very heavy rooster when she was too young and it broke her back. She still walked around - even while healing - but she looked like a camel walking, very bumpy. She lived for about 7 years, always called her "Gimpy". If your girl won't put her leg down, its not because it hurts - there is something else going on.