front door lock broke,,NOW WHAT???{{{{UPDATE}}}}}}

Hopefully you haven't sprayed anything into the lock.
Graphite is the appropriate lube for sticking locks.
Most auto shops or Ace Hardware will have it. You want a small tube with a small tip. Hold the tip against the lock opening, pry the little cover to the side if needed, and give the tube a squeeze or two.
Put a little graphite on the key and attempt to insert it. Try again if it doesn't work the first time.