It's like an inch long scar on my arm & it's been 4 years. i never really treated it, will anything work now?

Possibly: That scar is fixed and will on change on its own. You need the determine what you don't like about or short of not having it how would you like to see it different. A wide scar maybe able to be cut out and reclined to a better scar. A rasped scar may respond the steroid injections. A pink scar maybe get better with certain laser treatments.