@nonama
Just use the phone (just bought) or already been using it before this happen?

Why i ask just bought or already use? If just bought then he might not taken the plastic wrapping off yet and if already use before and suddenly got no sound, that might be something else.

Did you drop the phone or any major shock? Try restore using DFU mode. Sometime normal restore won't solve the problem.

One more thing, when you restore, did you set up as a new phone or use the iPhone backup (the question itunes ask when we first connect the phone after restore)?

Who's dat "frozenguy"????