What type of memory loss does an amnesia victim have? And do they ever forget how to talk?
Talking isn’t part of the memory, though having said that my own Father ‘forgot’ how to talk after an accident as a child and had to learn again.
But isn’t speech learned? Therefore any knowledge of speech has to be stored in the brain, right?
Sorry to hear about your dad. 
It was years ago and he was a quite a young child, I’m not really aware of the full details.
Speech is learnt but IIRC it is stored in a different part of the brain.
I can’t speak to long-term amnesia…but I’m missing about 18 hours of memory (apparently forever) from a concussion sustained while playing football in college.
I’m told I was incapable of remembering anything not directly in front of me. I could hold a conversation with someone while I was looking at them but if I turned away and turned back I would be surprised to find them there and have no idea what we had discussed previously.
It depends.
Retrograde amnesia is the inability to remember information stored before the traumatic incident. It’s not really like the movie or soap opera versions of amnesia.
Anterograde amnesia is the inability to create new memories after the traumatic event. The main character in Memento suffered from anterograde amnesia, although such people usually aren’t quite as high-functioning as he was.
In 1995 I suffered a traumatic brain injury in an automobile accident. I cannot remember most of the events of my life from 1985 until 1995. For instance, I could not remember the details of my wedding day in 1989 but I remember all the details of the converstion that I had with the policeman that arrested me for DUI in 1987. I got a “B” in calculus in 1992 but after the accident, they had a hard time explaining to me that 7+5=12. I had to relearn to read (My Little Red Reading Book, Dr. Suess, etc.) and I had to memorize the multiplication table over again. Prior to my accident, I was a quality engineer, expert in industrial statistics. I was able to take an entrance exam and go back to college in 2000 as everthing I ever knew to make a living was gone. It’s just as well, I’m learning civil engineering now because manufacturing is going south of the border or to China. It is my experience with amnesia that all the things you really want to remember are gone but all the crap you would just as soon forget stands up in the front row and waves at you.
If you are hit on the head hard enough to lose a substantial amount of your memory that is the least of your problems. For about two years my wife had to dress me and feed me and wipe my ass. I’m much more independent now. 