What I am understanding is you are using a GPIO pin connected to a motor to operate it, without any interface between the pin and the Pi. The results you are getting is exactly what I would expect, nothing. It is also highly possible you managed to destroy the GPIO pin as they are not designed to drive loads especially inductive ones.
The easiest solution would be to use preferably a non darlington NPN transistor rated at enough current and voltage to comfortably power the motor. Since I do not know the motor ratings etc I cannot recommend a transistor. I would suggest you use a NPN transistor something in the 1A or greater range, depending on motor rating. Connect the emitter to ground, the base to the GPIO using something in the 300 ohm range. The collector to the motor and the anode of your flyback diode. Connect the cathode of the diode and the other motor lead to the + supply. The + supply can be whatever is reasonable, it does not have to be 3v3, just be sure the grounds are connected.