What would have happened in the years following the war if the American revolutionists had lost the Battle of Saratoga and not gained French support?

If the colonists had not won the Battle of Saratoga and,
with it, French support, they would almost certainly not have won the war.  Therefore,
the years after the war would presumably have seen the colonies continuing to be ruled
by Britain.  This rule might well have been harsher than it had been before the
Revolution.

French assistance was vital to the US cause. 
The French gave men and materiel and also provided very timely naval support that (among
other things) allowed the colonists to win the Battle of Yorktown.  If this support had
not been given, the colonists would likely have lost the
war.

If the colonists lost, the British would probably have
cracked down on the colonies, at least in the short term.  If they had, the years after
the war would likely have been fairly oppressive for the colonists.  They would likely
have lost their ability to govern themselves in any significant way.  Taxes and
regulation might well have increased.  In short, the post-war years would surely have
been a very dark time for the colonies.