This question already has an answer here:

In Captain America: The First Avenger, Bucky dies before coming back as The Winter Soldier in Captain America: The Winter Soldier.

Why was he chosen to become The Winter Soldier and how was he resurrected after his death?

merged by Napoleon Wilson Oct 27 '15 at 23:19

This question was merged with How is Bucky even alive? because it is an exact duplicate of that question.