IPhone 4S not sending pictures?

Whenever I try to send a picture to my friends I hit the camera button in the messaging app, but the picture never shows up. It doesn't show up if I just hit send photo, and it doesn't show up if I hit add comment. Sometimes when I hit add comment a square where the picture should be will pop up and say "tap to download" but when I tap nothing happens. And so I just send it and it'll come up as a blank text bubble, and my friends say they never get it. Pictures won't send on iMessage or regular text message. I have to use snapchat and Facebook to send pictures to people and that's really annoying. My phone was sending pictures just fine before, so I don't know what the problem is. I can receive pictures, but I have to tap the pictures my friends send me in order to download them and look at them, and I never used to have to do that either. I've restarted my phone many times and even resetted the network settings on my phone because I read something that said if you do that you should be able to send pictures, but that didn't work. Does anyone know what the problem could be?

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