What role did Woodrow Wilson, the rservationists, and the irreconcilables each play in the eventual defeat of the Treaty of Versailles in the U.S. Senate?

Your other question was homework and so is this one.
Read this sticky on homework: https://www.askmehelpdesk.com/math-s...board-b-u.html

Now to find your answer there are very good sites to search, listed below:
Librarians' Internet Index
Refdesk.com ... Reference, Facts, News ... Free and Family-friendly Resources
ThinkQuest : Library

In the U.S. it was widely felt that the treaty was too harsh and there was still strong feeling that this treaty was a European problem. The two biggest opponents of the treaty were Henry Cabot Lodge and Woodrow Wilson ( because of the alterations the US Senate proposed to the treaty). Others doubted that the treaty could honestly provide peace. Edward M. House, the American diplomat that Wilson entrusted with preparing
A constitution for a League of Nations. In October 1918, when Germany petitioned for peace based on the Fourteen Points, Wilson charged House with working out details of an armistice with the Allies. House said, of the Treaty,

"I am leaving Paris, after eight fateful months, with conflicting emotions. Looking at the conference in retrospect, there is much to approve and yet much to regret. It is easy to say what should have been done, but more difficult to have found a way of doing it. To those who are saying that the treaty is bad and should never have been made and that it will involve Europe in infinite difficulties in its enforcement, I feel like admitting it. But I would also say in reply that empires cannot be shattered, and new states raised upon their ruins without disturbance. To create new boundaries is to create new troubles. The one follows the other. While I should have preferred a different peace, I doubt very much whether it could have been made, for the ingredients required for such a peace as I would have were lacking at Paris."

So the United States did not join the League of Nations, and as Wilson predicted there would be, there was another war within 20 years.

There is another article you should read that explains the political battle Woodrow Wilson faced with the ratification of the Treaty of Versailles:
Welcome to The American Presidency

Scroll down to the section called, The Peace Conference, Treaty Fight, and Retirement, 1919–1924.—