How do you ask a guy if somethings wrong?

I'm assuming that the context is that you have a bf or a crush and he seems upset as of late and you are concerned about him? Try to get him off to the side or alone for a few minutes, and ask him. Be like, "I've been noticing that you seem kind of upset/down/out of it (you can choose the Wording yourself) lately. Is everything ok?" Most guys will confess at this point if something is bothering them. Sometimes, however, a guy will be embarassed to tell you what's wrong, either because they are proud or just because it is a private matter. If he insists that he is ok or tells you not to worry about it, just say something like, "Are you sure? Well, you know you can talk to me if something's wrong." Even if they won't tell you what's going on, they will be touched at your concern and may remember it at a later date.