Is it true that John Paul II restored the practice of selling indulgences in the Roman Catholic Church in 2000?
No. It is not true. In any way.
The sale of indulgences is the sin of simony (selling of holy items) and the temporal punishment is the immediate excommunication of the perpetrator by the very nature of the act. Even accepting money for indulgences has been outlawed since the Council of Trent, which codified it with "let all who disagree be anathema".
After Vatican II the question of how the Church would handle indulgences was left up in the air. Paul VI, in 1968, realizing that there was still some spiritual benefits in them, produced a new list of things which included partial or a plenary indulgence (assuming appropriate circumstances). They no longer equate to "years of penance"* but rather, "part of the suffering of a soul in purgatory" (partial) or "all of the suffering of a soul in purgatory." (plenary)
The item you are probably referencing is that John Paul II released a new Enchiridion of Indulgences, which is the official list of all of the indulgenced acts from the Vatican. Individual ordinaries (heads of diocese, which can be any priest if necessary) are free to amend this within their juristiction.
* as an aside: indulgences are more properly understood as having to do with the amount of suffering in purgatory, not the length of time there.