A little more information please.
It doesn't ring for calls, texts, emails, notifications, or anything?
As for texts, and emails, since you say you are getting the reminders with sound, I would say it's a setting or operator error. Don't take that the wrong way, could you just be missing the ring, maybe due to volume levels? Then when things are calmer your able to hear the reminder? This could also be a settings issue. I don't know if you're running stock apps or third party apps, but in third party apps you can often have separate sounds for incoming and reminders. I would start with your phone sound profile. Something like (I don't have my phone with me to know the exact names) menu>sounds>sound set up/profile. Just double check your levels, and make sure they all sound at the levels you want. Do this by touching each one and the default sound will play at the level you have set. You may find one has no sound even though it shows a level. Then you can back up from there and set a new default that works. If that's not it, try going into the app you are having issues with and check the incoming notification settings. Some apps will have independent volumes. Also check your sounds here, because most apps offer you the option to use the default sound or a custom sound. If everything is working both phone settings wise and app settings wise, send yourself a text or email and see if you hear it while waiting for it, and see if the phone vibrates correctly when received.
As for calls I would do the sound profile steps, and if you are still not getting the ring ask someone to call you to be sure the phone responds when a call is inbound.
Not know much about your problem I would say one of these will at least point you to the problem. Post any findings or more information and we'll get you straight.
