Q: Imsg won't send from phone number

If you can't send or receive messages on your iPhone, iPad, or iPod touch - Apple Support

If you get an error when trying to activate iMessage or FaceTime - Apple Support

Dbhogs wrote:

 

I have tried those, but those usually help if the phone number is in grey or there atleast but my phone number is in grey with a loading circle and has been like that for about 3 hours now thanks though!

When your number is grayed out with a check mark that means it is the default.  However in your situation imessage isn't activated using your phone number.  Look at the 2nd link I provided, if still doesn't activate after 24 hours, you will need to contact Apple support.