I tried changing my mobile number and when I did now I can no longer send out text messages receive them and I can’t call anyone and no one can call me

How did you try to change your mobile number? Did you change it with your carrier? The SIM is what carries your account information, including your number. If you did not work with your carrier to change your number, that is probably why. Phone calls and text messages are a carrier feature and they would need to help you troubleshoot the problem.