By the great words of Master Yoda---. Death is a natural part of life. Rejoice for those around you who transform into the Force. Mourn them do not. Miss them do not." -# RIPCarrieFisher
Despite the fact that his body did not disappear, however, Qui-Gon's spirit was able to live on in the Force after his death, returning to instruct Yoda and Obi-Wan after the destruction of the Jedi Order.
From Qui-Gon, Obi-Wan and Yoda learned how to become one with the Force at the moment of their deaths, making their bodies disappear and returning as Force ghosts. The Force is dark today The Force will always be with her