I keep learning English and in my book i have a sentence to translate without any context, so it looks like:
Whose child is in the/a village right now? - Ann and Peter's child is.
So i wonder, in this case it wont be a mistake to use both articles? I mean it can be like "in a village" same as "in the village" ?
Let's make sure we understand what 'context' is. Context would be the surrounding text that helps us understand, or adds meaning to a quotation.
When you use any noun with a definite article your audience should know what you are referring to - either because you've mentioned it already (context), or because it is obvious. Consider this - if my opening words without any prior context were "the sun is bright today", you wouldn't ask "which sun?". So you don't necessarily need context to use the definite article.
Conversely, prior context does not mean you must use the definite article either. For example, let's say you've just spoken about a trip you took on a boat. You could reasonably ask your audience "have you ever been on a boat?". Just because you've already mentioned a specific boat that you've been on doesn't mean you'd expect your audience to have been on the same one!
So the only scenario in which context affects your choice of article is if you've previously mentioned something specific and you are intentionally referring back to it.
With your example, which you say has no context - if your audience is already aware of a specific village and you intend to refer that specific village, then say "the village". If your intention is to ask if their child is in any village, regardless of whether some other village has been mentioned or would be assumed to be the obvious subject, then use the indefinite article.
