I'm guessing you're asking about a ceiling fan. Could be wrong. But to check it you need a multimeter. Do a continuity check from N to ground, and from each winding. Then to a continuity check across each speed to N. If I remember correctly the slower the speed, the higher the resistance. If it shows continuity to ground then it's toast. If it show OL from any speed to N, then it's toast. If each speed reads the same amount of resistance, then the windings have shorted together. Also check the capacitor. Now, in the event you aren't talking about a ceiling fan... this should still work. Unless we are talking about ECM motors. Those are more complicated but much less common.