I broke my Ignition Key in the lock..
 

Uh its my neighbor's car..and not a Mercedes, but the post "counts" since I was working on my Mercedes when I was approached by my neighbor, who is on a tight budget and depends on this car for transportation and she won't let me return to reinstalling my transmission until I get this done..the lady broke her key in the ignition lock. However if I place the remaining portion of he Key in the lock, I can start the car, etc.

The car is a 1988 Corolla..

Is there a procedure or hope of extracting the broken part of the Key?

I broke my Ignition Key in the lock..

Carrameow

Sometimes a magnet will work.

Louis.

Ok, you did not mention how much if any you can see of the piece in the lock...
Some possibilities....
tweezers,
two ice picks to pry it out,
if you think you have a little flat area on the other part of the key, maybe a drop of superglue and stick it back in overnight...
start the car and drive it to a locksmith...costs less than a service call ....

Forget magnets, most, if not all, keys are brass. Bite the bullet and pull the steerwheel, take apart the turn signal mechs and remove the lock cylinder. It's probably worn enough that it needs replacing anyway if it's sticking keys and breaking them.

Otherwise, the locksmith is probably the next best idea, but she'll break another one if she doesn't replace the cyl.

Come to think of it, on a Toy, they might be able to replace the cyl without removing the steerwheel and half the steering column?