Please help me to give me sentence structure detail as following
Nothing I did would ever satisfy my father.**
"did" <-- is it emphasizing word , it like I "do" have a problem isn't it.
Nothing [(that)I did] would ever satisfy my father.
The bracketed bit is a relative clause, in which "nothing" is object of "did". In other words, "I did nothing".
The emphatic version would be:
"Nothing [(that) I did do] would ever satisfy my father.
Here, the relative clause means "I did do nothing", where "did" is the emphatic auxiliary verb. Note that the main verb changes from "did" to "do" because it follows the emphatic auxiliary verb "did".
Here, "did" is used as a simple past of the verb "do". In order for "do" or "did" to be an intensifier (emphasizing word), there has to be another verb in its original tense that becomes intensified by the "do" or "did" as in, for example, "I did do my homework," just like you wrote in your question.
The sentence structure, I believe, is like this:
Nothing I did ➔ subject clause
would➔ past tense of an auxiliary verb "will"
ever ➔ adverb
satisfy ➔ verb
my father ➔object