How to determine bipolar stepper motor wiring (came from a 3.5 inch floppy drive)?
4 wires indicates bipolar windings. There are only 3 different ways the coils could be wired (1-2 + 3-4, 1-4 + 2-3, 1-3 + 2-4) so just try each combination until it steps. If it doesn't step continuously in the same direction then reverse the polarity of one winding. If it goes backwards then reverse both windings.