Have had my 4s since just before xmas. I finally figured out how to load custom tones a few weeks ago, and everything was going well until yesterday and now for no apparent reason to this iPhone noob the sound no longer works on all my message alerts.
Ring tone is still working though.
I read online this seems to be a known os bug but I have tried resetting restoring etc and it's still not playing ball.
Any other ideas short if threatening the phone with a bowl of water?