Hi there upendra149,
Being able to send messages is important, and we'd like to help however we can. Let's start with ruling out some basics:
- We see the article above your post, but are unsure if you've already tried the steps listed in it. Please let us know the results after taking these steps: If you can't send or receive messages on your iPhone, iPad, or iPod touch
- If you have a compatible model, the latest version is 14.7.1. You can verify this within Settings > General > About. Here's a link that'll show how to first back up, then Update your iPhone, iPad, or iPod touch.
- When did this first start?
- As you're having an issue with sending SMS(green) texts, this usually deals with the carrier's side of things. The first link above has some things to check with your carrier, and let us know what you uncover.
We look forward to hearing about these issues, and take care until then!