Try this:
Go to Settings > Phone and make sure the number here is correct.
Go to Settings > Messages and turn off iMessage.
Go to Settings > FaceTime and turn off FaceTime.
Restart your iPhone (power it off and back on again).
Once the phone has restarted, check Settings > Phone > My Number again to confirm it is still showing the correct number.
Go back to Settings > Messages and turn iMessage back on.
Go to Settings > FaceTime and turn FaceTime back on.
Wait a few minutes for the services to activate with the correct number.
Go to Settings > Messages > Send & Receive.
Under "You can be reached by iMessage at" and "Start new conversations from", ensure only your correct phone number is selected, and deselect the old number or any incorrect email addresses if they appear.
If the issue persists then reset Network Settings: Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings.
Note: This will erase all saved Wi-Fi passwords and network settings. You will need to reconnect to your Wi-Fi networks afterwards.
__________________________________________________________________________________________
If someone has helped you then please click on the LIKES button in their post.
If you need help please provide as much information as you can
