Master Care Automotive Auto Value Changed spark plugs and broke off spark plug making my engine useless! Pine River Minnesota

You're speaking of the Ford two piece spark plug, Ken.  However, one piece or two piece the person took the car to a business which markets themselves as mechanics.  As such, the shop assumes the liability to do the job WITHOUT causing damage to the car.  Since they are marketing themselves as mechanics, the friend of the OP trusted them to know what they are doing.  Whether it was the two piece plug or a one piece plug, they are supposed to know how to get it out of the engine.  Yes, the engine can be ruined IF it was started after the plug broke off.  To me it looks like a clear cut case of negligence on their part.  A reasonable person would think a mechanic knows how to remove a spark plug, that's why she chose a mechanic.  For them to just walk away and say "sorry" is not the solution.  She needs to be made whole.  Any repairs to replace an engine needs to be covered by the party responsible for causing the engine to be replaced.  In my view, this friend needs an attorney to go after that shop and make that person whole.  I would also suggest the victum, as part of a settlement require a dealer repair/replace the engine as well as having the culpable shop reimburse the victum for ALL expenses such as job hours loss and attorney fees.  If the shop started or attempted to start the car or rotated the crankshaft after the plug broke off...oh what a wonderful case that would be! 

Here's a link to the problem     http://www.wsbtv.com/news/news/local/ford-drivers-sue-over-troubled-spark-plugs/nMkL2/

There is also a special repair tool that most Ford dealers have to remove the broken plug(s).  It's a BIG problem for Ford and is apparently a weakness in the spark plugs they used.  Good luck and my guess is the shop is right.

What make, year and model is the car?