According to LDS teaching, Peter, James and John conferred upon Joseph Smith the Melchizedek Priesthood shortly after John the Baptist had conferred upon him the Aaronic Priesthood.
The title of the page is "The Priesthood of God Returns to the Earth". However, LDS teaching also states that the Apostle John never died, but is still alive on earth today. Since John was one of the three who conferred on Joseph Smith the Melchizedek Priesthood, it seems to indicate that John himself possessed that priesthood. Since John was still alive on the earth, it would seem, then, that the priesthood never, in fact, left the earth and, therefore, could not be returned.
So, what does the LDS church mean when it states that the Priesthood returned to earth when it was conferred upon Joseph Smith?