As far as I know, when we can't remember the name of a person or when we didn't hear it properly, or even if we never learned the name of a person before, we can say "What was your name" to that person by backshifting the verb (This can be done in my native language in this question and in some other questions too. It can be done in any question where we can't exactly remember the answer of actually.). Can we do the same thing in all other kinds of questions too (this is my main question to you)? For example, can I say these sentences below?
"Where were you from?" [Can I say this in any part of the conversation (at he beginning or wherever) even when I am sure that I was never told where the person I am talking to is from?]
"Had you been to USA?" (Can I say this sentence when I sort of remember that the person I am talking to has been to USA but I am not sure? Or can I say it even when I merely wonder if he has been to USA? I mean even when I have no idea if he has been there or not, when I am sure no one ever told me he had been there or not.)
"Did you play guitar?" (I guess I can say this just like the ones above in a situation where I like remember that that person plays guitar but I am not sure. But I am not sure if this one can be said when I merely want to learn if somebody plays guitar.)
"Was your name pronounced as 'John'?" (My questions are the same on this one as the ones in the parentheses above: Can I say it either when I want to learn the pronunciation for the first time or when I can't remember it? *Context: Let's say I am asking this one of a Swedish person.)
From what my ears which are sort of used to hearing English (American English especially) tell me, English and Turkish are similar in terms of this. I think in English, just like Turkish, we can backshift any question when we feel like we knew something but we can't remember it. And also again just like Turkish, when we are sure we never knew or heard about the thing we are going to ask about, when we merely want to learn something for the first time, it is wrong to use the backshifted version except for some questions like "What was your name?" Maybe in formal contexts, all questions where we are wanting to learn something for the first time can be backshifted. I don't know.