It sounds odd to ask that as a question. "Why nobody had asked me" could actually be used in English to start off an explanation, but I wouldn't use it in a question.
I can imagine phrasing the question like that putting stress on all first words (perhaps even adding 'ever'). The phrase already is weird, who ever heard it in the past perfect?
Just to clarify, in a negative sentence, you use 'no one' or 'nobody' with the positive form of the verb. You can also express the same thought by using 'anybody' with the negative form of the verb. So... "Why did nobody ask me?" means the same thing as "Why didn't anybody ask me?" :)
I agree, Kookkaren. In this example, we could say either "why had nobody asked me?" OR "why hadn't anybody asked me?" without any difference in meaning.
If we remove the question mark (and the inquiring tone), "perché" changes from "why" to "because". Perché nessuno mi aveva chiesto = Because nobody had asked me.