All is working for me. Have you tried settings > apps > messages > "force stop," then go to storage and clear the cache? Restart the device.
Since you've only said "not working," I'm giving general troubleshooting advice. If the above advice doesn't work, providing what the issue is/any error codes would be useful.
Hi, as I open the app and then go to write a message it goes straight to the home screen. I will try what you said now and see how if it works. Thank you.