If you are recovering from amnesia what are the chances that you will forget things forever?

I have a friend who recently hit his head. He said that he has "dissociative amnesia and mild retrograde amnesia" He DOES remember me from 2 or 3 years ago but is starting to remember a little more from a few months ago. He was telling me about a seminar he went to about amnesia where people who had it asked questions and get info. One thing that seemed alarming was that he said that there is chance that my friend may forget a few small things forever. What are the chances of that happening?If you are recovering from amnesia what are the chances that you will forget things forever?
Three years ago I was in a accident where I was pulling across an interstate and I pulled into the path f a 4x4 truck that was traveling about 65-75 miles and hour and as a result of that for about 2 months I was in a complete daze and a state of confusion I felt like a walking zombie.

Over the first year I was so lost on everything - I couldn't remember peoples names, I would recognize them and would know I knew them but I drawed a blank.

Even to this day I have lost alot of information that I use to know, like dates and times of jobs I have had and what all I have done in anykindd of order - I can't recall my past and what I have done and where I was. I have not ever been to the doctor for any of what I am going thru and I have no clue if I will regain anything back but I wonted to share with you that I have since the accident been able to retain current information and I am like a sponge when I am learning something I learn it and theexcelll in what ever it is I was taught. So I feel ok with knowing this and pray I don't have another accident that will take all I have learned away again....lol