how do i reload entire nano 7 program... its wiped out

not sure how it happened, but lost all of the entire data on my nano 7... needs to be reloaded all over again... any way to do that? ive tried everything to bring it back, but all i get is do not disconnect, and ok to disconnect. its like it never existed. did i wipe it all out? is there any way to bring it back? please advise... thanks so much!