Why is my phone not delivering pics & messages?
Delete those messages. Long press on the message bubble and choose "More". Then tap the trash can and delete that message. If you don't see a trash can, then swipe the messages app out of the multitasking tray. Then try again. Once deleted. Try sending the pic again. Is it just photos you have issue with? Do messages without photos send OK? Regardless, try Reset Network Settings. That may help. And check your wifi or cellular signal. If it's weak, that may be the problem. To Reset Network Settings:
Reset Network Settings
Settings>General>Reset>Tap Reset Network Settings. You may need to enter your wifi passcode back in afterwards.
Sent from my ancient but trustworthy iPhone 5. ☮