Jerking off to porn, that thing too sweet!

In my teens, I would get an erection so hard it would hurt, from seeing something erotic or the mere thought of it.
But over the years I've come to notice that I am unable to get erections from visual stimulus or erotic thoughts. That is I can't get an erection from what I see or think about.I only get an erection by manual stimulation of the penis that is by touching or stroking my penis.

I do not know if it is really that much of a problem but I know jerking off to porn over the years caused it. I would like to know if I can change the state of things? and are there others with the same issue?

medical opinions please.

Yes, you can. With the right mindset, you certainly can; It's mostly in the head. But, you'll have to give up porn and masturbation — They are as deadly as they get. It is not easy, but you have to do it. Also, be prepared to be struck with the memories of it when you are on your path to abstinence, but be equally prepared to fight them off.