IPhone isn't letting me text?

Recently this morning, I texted one of my friends that has an iPhone (iMessage, Blue and gray) and it went through (the text), and I also texted another friend which doesn't have an iPhone (Green and gray text) and the 'Message Send Failure' pops up. I tried to resend it but it didn't work. I also tried to power off and on but that didn't work either.

Maybe you've run out of credit? Or it might be the new update. Do you have 3G/Wi-Fi because that could also be the case.

  • Why isn't my iTunes letting me get songs on my iPhone? Whenever I download a song, or get new music, it shows up in my iTunes on the computer, but after syncing my phone to iTunes the music doesn't show up on the phone. I don't know if this is important, but, I share an iTunes account with my dad and sister, I've gotten the most recent updates on iTunes, and it's an iPhone 4S.
  • Why isn't my iPhone letting me text other phones (non iPhones)? When my phone isn't paid I noticed I could still text like usual but only if IIm connected to the Wi-Fi, for some reason now all it says it message not deliverd when I text someone without an iPhone but when I text someone with one it sends automatically.
  • Why isn't my iPhone letting me download apps? I've been trying to download some apps on my iPhone and it's not letting me for some reason. I tried restarting my phone and it still doesn't work. I'm not sure if it has anything to do with it but before this happened I updated my phone to IOS 8.4.
  • Why isn't my 16gb iPhone 5c letting me save pictures from the internet? When I go on google images I hold the picture until the little menu pops up but the save image option isn't there and I've added it to my reading list and tried again it didn't work either and I just deleted a WHOLE BUNCH of photos my phone is on iOS 7.1 so I don't know what the problem is Please Help ME!