Firstly, Have you lost all fan speeds or just one?
Does it look like the resistor coils on the fan speed resistor have broken apart?
Fan blower motors usually have a 2 pin plug that powers the motor, you can test with 12v.
Being quite a few years old it may be low on brushes, put your fan speed resistor back in, turn the switch on and give the back end of the blower motor a tap to see if you can free the brushes. May start working then which is a good indication that the brushes need replacing...