If the immune system mediated an aggressive attack on the whole peripheral nervous system and killed the entire nerves of the body what are symptoms ?

Death: Although i just answered your question, important to understand that this would involve a rare progressive irreversible anaphylactic allergic reaction, and this really affects numerous organ systems. However, consider that there are chronic immune disorders that attack peripheral nerves (cidp), and nerves in central brain and spinal cord (ms). This is almost never an all or none situation.