update
run the command winver, what it says, there was a update last year to that version that made external drives of that size to be rocgniced as raw and won't work but if you connect them to another pc running 8.1 or win 7, it works perfectly
if you have windows 10 updated, all up to date, and this keeps happening, the hard disk is damaged
s¿remember not to buy seagate in the future, it happens with their hard disks alot this thing and being 1 year old surelly no warranty applies
you could try a couple of partition restoration apps but if the head itself is not moving, the app will not magically will make i move
if you are sure it is not under warranty and you really need the files, there was a time when people recommended , hit it against a table in one of the sides
sometimes makes the head works but most times finishes the damm hard disk, kills it completely 😀 destroy it at your own risk