1) Use a voltmeter to check there is power on the wires leading to the fan.
It's a good idea also to apply a load of some sort, like the bulb I suggested. Occasionally you'll get a near-normal voltage reading as a result of capacitive coupling. When you then connect the fan and the voltage drops to zero, you will assume the trouble is in the fan
2b) If there is no power, check the wall switch. You can carefully take the plate off the switch and use the voltmeter to check for power there.
In case you're not familiar with such, Heren, what Eng means here is to check for voltage from neutral to each terminal of the switch. Of course when it's on you should get the same reading for both
Often the neutral runs insulated in the wall behind the box so you have to make this connection somewhere else, such as a nearby outlet (the wider slot). Or you can connect instead to the metal frame of the switchbox. However, there's no guarantee the box is grounded