Question
After my Orchid has lost all of it's petals, will it bloom again? Do I need to do anything to the stalk?

Answer
Janet, You should do two things: repot your orchid in fresh orchid potting mix in a well drained pot and cut the old flower spike above the second or third node (ie joint) in the flower spike.  Some spikes remain green and could bloom again while other spikes, based upon genetics, will dry up and die back.  If it remains healthy, it should bloom again next year, if not before,  The purpose of repotting in an or chid potting mix is to help ensure that it remains healthy.