IMessages aren't delivering?

Usually when I send messages on my iPhone it says deliver underneath but every time I text my friend who also has a iPhone, it never delivers. What's wrong with it? And my phone is a 5c and it's updated. My phone never has problems sending it to anyone else. But anyways what's wrong?! Why would it send?!

This happened with my my iPod touch 5th gen. I don't know how well this strategy works but i just went through my setting and played around with things like airplane mode and Wi-Fi. LOL

  • Why is my Iphone not sending as Imessages and receiving iMessages from one person? I'm texting my wife and we both have iPhone's and she is getting the messages as an iMessage but the ones I'm sending her on my end show up at green. Sometime it will go as blue, get the little red exclamation point then send as regular SMS. I'm texting someone else too and she has an iPhone, and she is getting mine as regular iMessages and mine are sending as regular iMessages. Why aren't they sending to me wife as iMessages?
  • Why is my IMessage sending but not delivering? I have an iPhone 4 and I'm trying to text a friend and I text them and it says delivered but then a few seconds later it says not delivered. It is doing it to only this one person and it randomly started doing this. When they text me it comes in as text. How can I fix this? What is wrong?
  • Why aren't my iMessages in a blue bubble? Usually when iMessaging/texting somebody else with an iPhone, your messages are in a blue bubble. I have a friend who also has an iPhone, but when I text her my messages aren't in blue. Is there a reason for that?
  • Why aren't my headphones to my iPhone 4s not working? I just got the iPhone 4s a couple of months ago. I haven't even touched my headphones until last night, & they're not working? I'm trying to listen to Pandora. I dunno what's going on. It seems if I screw in the headphones extra tight and keep hold it plays through the headphones for a second. Anyone else have this problem or know why this is happening?