Not sure about your particular model but most of my drones have three wires running from the ESC to the motors and if there in the wrong sequence the motors can go anti-clockwise ,reversing the wires will make them go clockwise.
The correct configuration is as in the picture below:
Does the motor turn at all? If it goes the wrong way, reverse the wires. Your drone has DC motors, not multi phase AC with 3 wires as suggested by someone else.
If the motor is not running at all, most likely the motor driver has failed. I think these are hard soldered to the main board on these, so you might need some specialist help to fix it. Worth checking the wiring has not become disconnected or shorted out first though.
I didn't suggest the SG900 had three wires , I wrote " most of my drones have three wires running from the ESC " . I was pointing out that by reversing the wires or in my case re-aranging the wires would make the motor go in the opposite direction.
Its actually my friends drone , it looks like its spinning like the rest ok till u try to take off and it won't lift that corner and there seems slight less go about that corner , think hevhas given up and bought another but thanks for ur help