This is one of the fundamental existential questions. The answer to this question has become one of the most controversial subjects for followers of Srila Prabhupada because the GBC have taken a position that is opposed to guru, shastra and sadhu. Moreover, their position—that the jiva falls to the material world from Goloka Vrindavana where she is in direct contact with Sri Krishna—creates many doubts in the minds of followers of HDG because this position directly contradicts numerous statements of shastra.
It is true that Srila Prabhupada was equivocal on this topic. Since that is the case our siddhanta tells us to consult guru, shastra and sadhu to reconcile the apparent contradictions with them. Those who have done so have come to the unmistakable conclusion that all of our acharyas, as well as numerous statements of shastra, explain the origin of the jiva as that of the tathastha-shakti, and that the jiva never returns to this material realm upon achieving emancipation to Goloka Vrindavana.
On the right side are links to detailed information. Not all that is available is presented here. One of the first books on the subject is "In Vaikuntha Not Even the Leaves Fall" by Satyanaran Dasa and Kundali Dasa. This book is available in Loi Bazaar and other places online.