Rear axle

Wow! How did that happen? Well firstly, was suspension components affected when the rear axle came off? If the were you may need to replace suspension arms, shocks or springs if they were damaged as well. If the car uses leaf springs, they might need replacing along with the rubber bushings and u bolts that hold it down as well. Secondly is the rear axle also a drive axle and does the rear wheels send power to the road? If it is you might need to replace drive axles which connect to the rear axle and the wheel hub. There are a lot of parts making up the rear axle and it is a major component of the car as well. Unless you know what you're doing, you should probably bring the car to a shop since it is such a big task and there are many components that make up the rear axle.