When you say its a 2" well pipe, do you mean the diameter of the pipe attached to the handpump, or do you mean the size of the pipe going into the ground?
All you need to do is pull up the handpump body to retrieve the parts. For example, I have a 4" windmill well casing (the outer pipe). Into this pipe goes a 2" inner pipe which has a brass cylinder screwed to the end. The cylinder has the pump piston (sealed by leather piston rings) capped within it. Attached to the end of the piston rod are the sucker rods either wood, iron or plastic. The inner pipe is held in place and at depth by the amount of pipe clamped at the end of the handpump up on top. The hand crank on the pump is attached to the top end of the top sucker rod. So, to retrieve a fallen sucker rod, all you need to do is pull up on the handpump and grab the sections of the feed pipe as they come up. Keep this process going until you pull the brass cylinder up out of the casing.
If the well casing is 2", then the inner pipe is probably 1" and the cylinder is 1.5", etc. Its essentially the same as a modern electric immersion pump, instead of wires you have sucker rods. There is a casing and an inner feed pipe.
If you have "lost" the feed pipe (along with the cylinder and the sucker rods), then you are hoping to grab the inner lining of the feed pipe with a fish wire. Older wooden sucker rods are joined by an iron "H" type of bracket, so fishing is fairly easy. Newer ones are threaded. You pull up on the fish wire and hope that the cylinder and the feed pipe are not stuck in the mud and gravel at the bottom of the casing.
If you know that the inner pipe is OK (but down the well a few feet), you can see it. Then you can jam a pointed wooden 'stick' into it and pull it up. Windmill cylinders are usually placed just a few feet above the bottom of the casing, so that allows you to shine a light down the hole to see the feed pipe.
Sorry if this sounds a bit rambling, but I've had to grab a few feed pipes in many different ways. Each installer set the windmill well up in ther own way.
Hopefully you get the drift.
Then you can change out the feed pipe and sucker rod sections as necessary. There are a few windmillers around who still sell hex white ash sucker rods $4.00 to $6.00 a foot, depending on size. You are expected to buy either 120' or 180' of total length, with various individual lenghts in a package.