Why won't my iPhone 4 ring or light when it's locked?

When it's unlocked, it rings, vibrates and i get the notification but when it's locked won't vibrate, ring, or light up.

In my opinion, there are only 2 possibility's really. (1) it's on "do not disturb" go onto the settings and do not disturb should be right there. Just under half way down the screen so you shouldn't need to scroll down or whatever at all, make sure it's flicked OFF not ON.
or (2) it's broken haha

Go to settings Sounds & Haptics select Viberate on ring. This problem I thought was fixed for years, but has recently returned.

  • Why won't the ring tone on my iPhone 4 work? I got my brand new iPhone 4 the other day and I keep trying to set a ring tone on it, and when I select the one I want and someone calls, it won't ring. It won't even vibrate when I put it on vibrate. Its brand new, never been used, so I don't think it could be broken. Maybe its on a weird setting. Either way, when someone calls or texts me, I won't know because I can't hear it.
  • Why does my iPhone ring when I didn't actually receive a text? It happens sometimes, my iPhone will ring as if I got a text, and then I check my inbox but I don't have any new texts. Does this happen to anyone else?
  • Why does my iphone ring twice? Lately i've noticed that my phone will ring when i get a text… Then will ring again for the same text a few minutes later if i haven't checked it. its just annoying because it makes me think i'm getting two texts and only getting one… how do i fix it?
  • Why does my iphone not ring only vibrate? Also some apps have no sound. Do you think its the mute button is jammed but then again it says its on ringer.