IPhone 5 has no sound when receving calls or text?

So I just updated my iPhone 5 to the iOS 7, and for some reason, when I receive calls or texts, my phone doesn't make a sound to alarm me. ONLY when I'm using the phone, like browsing or using an app, it makes a noise when I receive a call or text. So when the screen is black and when I'm not using it, it doesn't make a peep. I've missed so many calls and texts lately. It's frustrating.

Can anyone help me figure out what the deal is? Thanks.

Added (1). And no it's not on silent.

You sure you didn't just bump that little corner switch that makes it mute?

Check to see if you have Do Not Disturb enabled. When Do Not Disturb is enabled calls and alerts that arrive while locked will be silenced, and a moon icon will appear in the status bar.

I've got the same problem but it's just when I'm receiving or making calls, I can't hear a thing

Thanks Markus. The @#$% switch is obscured by the case and somehow got flipped half-off.