Need help

I am testing my motors 3 of my motors are spinning great but one of my motors is not responding to throttle at all (on betaflight) the 4th motor any idea why? It’s a brand new motor bought with the other three. And seems like my rotation on 1 and 3 are wrong how do I go about fixing that through software ?. Should I get a new motor or is there any other way to test the motor??. Thanks