My blue budgie has a crooked neck. What's wrong?

I have a blue budgie that I've had for quite a while now, maybe a little over 3 years? Today, I discovered that it's neck is crooked. Not a little like it would just tilt to side side, I mean REALLY CROOKED. When I saw it, it's head had rotated 180 degrees. Is it normal? Could Sammy, my parakeet die? I just really want help. D: