If you require some information you can say:
Could you tell me if/when/how much/why..?
I wonder if you could tell me...?
I'd like to know..
I'd like some information about..
If someone asks you for information you can reply:
As far as i know,..
Well,(in confidence,) i can tell you that
I'm afraid i don't know.
I've no idea,I'm afraid
I don't have that information available just now,can i call you back?
I'm not sure,I'll have to find out,Can i let you know tomorrow?
I'm afraid i can't tell you that,it's confidentail.