Unfortuantly, there is not much you can do for amnesia. Although, you can possibly jog ones memory with a series of photo's or telling them things they don't remember. Otherwise, you'll have to start from zero and teach them everything they may not know.
DISCLAIMER!!!
I am no professional and the opinion stated above is not that of a professional. What I said above may not be correct. So please, do not hold it against me if I am wrong.