Most torsion axles lock into a splined base that is fixed. It would be like looking down into a 12 point socket. The other end of the torsion bar then slides into the splined end of the arm that the wheel is attached to, and pivots torsionally against the fixed end.
I have never seen one actually break, but I suppose it could. I would be more inclined to suspect that either the fixed end has broken looose, or stripped, or the splines on the trailing arm have stripped.
Sliding the torsion bar out will probably not be too difficult, reinstalling it and getting it up and over the torsion stop might be tough. This would be akin to getting a coil spring out of a control arm, or reinstalling one, without a spring compressor.
It can be done, we used to do it on VW IRS torsion units in sand rails, but you need to be very careful.....
If you aren't mechanically inclined, and don't have a few buddies who can help, I would suggest taking it to a shop that has the tools.