Often during the day I will notice a warning fro "Updates" and "Text Messages not sent", however in many cases the test were in fact sent.
I clear the warning only to have it reappear after new text messages.
Try dialing *228, option 1 in a good signal area to reprogram the phone to the Verizon Wireless network.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.