I'm not surprised that you are in crisis, after I tried to explain to you what all the parts are called so that you could describe the problem, you still manage to describe your problem in a non-understandable way.
Anyway, lets try this. I am not sure if a Puch has the crank spindle connected to anything inside the motor but I think it might, maybe someone else can help here.
Look at the crank where it fits on the crank spindle, there should be something like a bolt with a nut on the end, passing through the crank at a right angle to and next to the spindle. This is a cotter pin. It is a round steel rod with an angled flat on one side so that when you tighten the nut, it wedges the crank to the spindle.
Back the nut off a couple of turns until it is flush with the end of the thread, put something heavy like a big hammer under the crank and spindle, then whack the nut with a brass hammer. This should loosen the cotter pin. Then remove the nut and drive the cotter pin out. The crank will then come off the spindle.
Some rules. Cotter pins are installed with the threads in opposite directions. Cotter pins must have perfectly smooth flats, if you can't clean them up with a file, get new ones. Most bicycle shops should have them. With the left side pedal pointed forward, the right side cotter pin should have the thread pointed down, the left side, thread up.
If this does not make sense to you, describe your problem and have someone else read it before you post. If they are confused by "those puppies", we will be too.