What happens when a transmission of a car is destroyed?

What happens when a transmission of a car is destroyed?
You can't drive it until you fix it.

Your transmission is in between your engine and your tires. If it is destroyed, there is no way to transfer that power, and you will either be able to start the car, but not move it using the engine (i.e. destroyed an results in the car being in neutral for all purposes) or you will be unable to even start the car and certainly not move it (even pushing) if the transmission destruction results in the car being essentially stuck in gear or locked in position.

This could be deadly if it occurred on the freeway.

Have someone qualified check it out if you are even moderately concerned!