Thanks for the explanations!It depends what you mean by "classical", w-s-w. "What have I to do?" is not currently the normal way of phrasing this question in BrE.
"What I have to do?" is not a valid question in any variety of English. In a exam, it would be incorrect but I bet that in the colloquial speech is quite normal to find. I found it several times knowing that it is incorrect though!
"What do I have to do?" is indeed common (in both AmE and BrE).
Good observation , cause, with English we have a special phenomenon, so many people speak English in a non-native way as I do. I just want to say in regard, that I saw it so many times.No, in the colloquial speech of native speakers, "What I have to do?" is not at all normal.