title_body: Why did my cherry juice turn directly into vinegar while never being wine?
upvoted_answer: It's difficult to answer why fermentation did not complete without further information.
  
  It's quite possible the sugar content was too high and pH to low for whatever yeast was added to survive and begin fermentation.
  
  Vinegar however is created when bacteria that produce acetic acid are present in an environment with a sugar source and oxygen. They will thrive off of the sugar just like brewer's yeast, but will also produce acetic acid as a byproduct of their life processes.
  
  If you wish to make cherry wine, I would suggest diluting the juice down to somewhere in the range of a sugar concentration of 10 percent, measuring with a hydrometer or refractometer, and using a yeast, possibly a dry wine yeast, that can withstand alcohol in ranges of 10-14 percent abv.