What Can Be Done About Depressed Facial Scar?

I've been using Tretenoin but seems doesn't work. I think it had worsen the scar. It has an active ingredient for producing more collagen on the skin. Meanwhile, I've tried Dermatix but still some assert that it is not good for this kind of scar so I'd also tried Mederma.Which product is better?I really need help because this scar had caused me a lot of trouble. I was awfully depressed about it and it affected my normal functioning. I've been hiding it for many years whenever I go out. It seems that I'm imprisoned with this scar.