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.