After 1000 C.E. what were the causes of the revitalization of western Europe?
It could be argued that the rise of Western Europe doesn't really begin until the Renaissance which is several hundred years after 1000 C.E. The emergence of Western Europe is directly tied to the weakening of the power of the Catholic Church. The period prior to the Reanaissance is derogatorily referred to as the "Dark Ages" and there is little doubt the "darkness" was caused by the extreme control over thought and expression perpretrated on people by the Church.
You may recall that science was practically mummified for nearly a thousand years under the orders of Rome. While Chinese, Arabic, and Indian scholars were making huge advancements, western Europeans faced excommunication or death for challenging what the Catholic Church viewed as the "Great Chain of Being." This Chain explained everything anyone needed to know to live a good life and to move on to heaven after death. God was at the top and plants and animals were at the bottom. Within the human race kings and priests were at the top and the rest of us were below them. The Great Chain did not allow people to move up it. Where God put you is where you stayed. To allow movement was to admit that God put you in the wrong spot. Science was not to be used to explain God's creation. All we needed to know is that God created the heavens and earth in six days.
As the Renaissance, the Reformation, and the Enlightenment periods developed in the 14th century and beyond, the power of the Church was weakened. Art was no longer only allowed to glorify God (though there is plenty of Renaissance religious art), the Church was no longer the only path to heaven thanks to Martin Luther, and Locke, Diderot, Erasmus, Paine, and many other thinkers led a rise to freedom of thought and expression.
So as the church weakened, science, art, education, and commerce all rose leading to the great power of Europe which eventually conquered the rest of world during the age of imperialism.
There were at least two main causes of this revitaliztion.
The first was a boom in agriculture that was brought about by new technology. The most important advances in technology were the heavy, wheeled, iron plow, the horse collar, and the horse shoe. The plow made it possible to break up the heavy soils of Northern Europe more effectively. The horse collar and horse shoe made it possible for horses (rather than the much slower-moving oxen) to pull those plows. These innovations made agriculture more efficient and allowed the cultivation of more areas. This led to more crops being harvested which could feed more people.
The second was trade that was made possible by the agriculture and by better security in Western Europe. Agriculture produced a surplus that allowed more people to create things that could be traded. The improved security (stronger governments that could do better at keeping bandits from preying on travelers, for example) made it safer to trade.
These factors allowed Western Europe to become much more prosperous in this time that is sometimes called the "High Middle Ages."