I think your a little confused.
The 4wd shaft or propeller shaft it what is on the bottom of the clutch housing, and the part that came out on you.
You need to remove the front half of that shaft that goes to the front axle in order to get the two halves together, then after its together then you reinstall the shaft.
If you couldn't turn the shaft section that is headed to the rear it's still in 4wd take it out of 4wd and that shaft should free spin.
The PTO shaft is in the center of the clutch shaft, there are 2 shaft splines the inner is the PTO, and it engages a coupling on the back of the crankshaft, the outer splines engage the clutch disk, if both are not lined up it will not slide completely in, make sure the motor to the clutch housing are square to each other.