There could be any number of issues at play when you can't send a message on your Android phone or it fails to send pictures, including connectivity problems and incorrect message settings.

Reboot your LG G7 ThinQ If you were able to send and receive text messages before this problem started, it might be just a minor glitch. Reboot your phone if it’s the first time that it happened.

This is what you’re going to do if your Samsung Galaxy A9 can’t send or receive text messages… Force restart your phone first. Make sure your phone gets decent signal.