How do we learn our individual purpose in life and what if all that you have strived for, never happens?
This is a complex question that we can not really know for sure during our lifetimes. However, essentially, to know our mission we need to pay close attention to the things that happen to us, and consult the Torah for the proper way to react to those things. Having the proper reactions are our mission in our life. In addition, we carefully assess our strengths and abilities, and apply them toward doing the positive commandments contained in the Torah. These too are our unique mission. Thus, we see why a thorough knowledge of Torah, and an honest assessment of self, are essential parts of living a fulfilled life.
This is just the tip of the discussion, and if you are truly interested in living a fulfilled life, I suggest continuing your studies with a Study Partner.