Hi,
Unfortunately you are going to have to hope that some of his paperwork survives somewhere because there are no complete lists which can be referenced. What do you know about about his service? When was he born? Where was he living when he was serving? Any detail you can give will be useful but as I say, narrowing things down to the point where the information is useful to you is going to be difficult and will require luck. We can certainly try though. I'm assuming of course that you are talking about his service in the Hitler Youth?