van crank ok then put in reverse it jump turn ignition off now it will not crank

What is your question?

2005 ford freestyle crank up. put foot on brakes to put in reverse it jump. scare me so put back in park and turn off ignition. now will not crank. what can be wrong. I had it tow to shop they said transmission. but how could transmission affect the cranking. I just do not have much right now to get fix. it that what it is or something else