IPhone 4 sounds don't work when phone is locked?

I've had the iPhone 4 for about 3 months and it won't make sounds when it is locked. I don't have my phone on mute if that's what you're wondering. When the phone is unlocked and someone calls or texts, the sounds work fine. However, if it's locked it doesn't even ring and I'm always missing calls and getting voice mails because it won't ring. Any suggestions?

Is it on vibrate? If the red is showing flick it.

  • My sounds won't work on iPhone 5? Everytime I try to turn up/down my volume, it says there's headphones in and my sound won't work. How do I fix it?
  • IPhone help? Its cracked and locked up and buttons don't work? I have an iPhone that is locked up because of unknown password, neither buttons work and screen is cracked really bad and it won't connect to iTunes to reset. Any info on how much it would cost to have this stuff fixed? I can replace the screen myself but does anyone know how I can get into it?
  • Iphone 5c: No keyboard sounds, lock, or camera sounds I noticed yesterday. I don't know why this is happening. I check the settings and I have all the volume at max. Is it becauase I recently updated my phone?
  • Do exhaust sounds or muffler sounds sound different on camera? I have a iPhone 5s and I'm recording my new muffler exhaust on my accord. On person it sounds good. Deep and really nice. I had my girl rev it and it sounded nice, but when I record a video I can't hear the deepness on camera just the exhaust sound and it doesn't sound that nice! So which one is the real sound? Do videos really not capture the exact sound!