IOTL, the Conference of Vienna came to the conclusion that it was foremostly important to keep those pesky democrat movements down, and have a stable Europe with a balance of power. To achieve this, France was not punished but retained its pre-revolutionary borders, lest it become a centre of instability.
So, the question here is: What if the European powers decided otherwise? What if France has to cede territory, pay reperations, etc.? How could it come to this, and how would things go from there?