Can someone tell me how to get these two accessories because enterprise lets you have more than 9999 Hp and Invincible lets you do more than 9999 damage. and i need them badly!!!

well... i know that you get 1 invinsible in kilika

talk to the man on the boat with the camera in chapters 1 & 3 and in chapter 5 he will let you got to the island... invincible is in the chest that show up as a yellow box

You receive the accessory Enterprise if you don't visit the Moonflow during Chapter 1. At the beginning of Chapter 2 when you push the musicians into the elevator, Tobli will also be there. Push Tobli into the elevator before you push the three musicians to receive Enterprise.

Damn.. that sucks I missed both those things. Is there any other ways like stealing.

Those are the only ways of picking up the accessories Enterprise and Invincible.

You'll have to wait until your next game through, but luckily the whole thing is cumulative, so when you get the accessories, you'll still have them for the game after that as well.