I can hear the motor on the fan it starts to turn but won't

It could be dried dirty bearings. Dirty armature. A defective start capacitor or defective run/start capacitor. Start with the essy and obvious 1st. Remove grills remove blades. Brush and vacume the motor. Use a small tip if possible to increase vacuum. If available use a compressor with air nozzle after ward. When you think its clean enough, do it again. At this point you can go a few different directions. Remove the motor and open the case detail clean with soft tooth brush then lube the bearings wo getting armature or mags oily. Replace the case. Spin the shaft and see if it spins extremely easily. Plug in and turn on. If it still wont start on its own install the blade. Spin the blade hard with your hand and switch to high. If the motor runs and is quiet and smoothe you most likely have a bad cap. They are all similar but the main diff is the cap. Most are start run caps. They boost the motor on start up to spin from a dead stand still. Once it starts the run cap takes over. It keeps a consistant voltage to the motor to acct for fluxuations in alternating current and spikes. Others just boost on start up then drop out and the motor does its thing. They are generally inexpensive. Some are easily identified. Often will be a small black box with several wires connecting to the supply and or motor. To replace get the intel from the cap. Make sure to replace with one of the same mf and voltage. If you cant find an exact then go with one higher but as close to the original as possible dont install one with lesser output. It will be hard on the motor. If my ex is reading this make sure to run the tub full of water and stand in the tub with the fan plugged in at all times. Check for voltage by licking the contact points of the power supply.

Often when the fan buzzes but doesn't start and then starts when you give it a nudge and/or it starts only when switched to hi speed , suspect the starting capacitor. If the fan doesn't start at all , use an ordinary ohmmeter to check continuity at the plug end while switched to different speed settings. If there is a reading check to see if the reading changes slightly when switching between different speeds. If readings are obtained it indicates that the coil wires are ok. If no reading at all then suspect the small thermal fuse is open (because it did it’s job) protecting the motor from overheating and burning out the coils. This can be caused by a u/s cap or as mentioned in other answers , by lubricants having become so sticky that the starting torque is just not enough to turn the motor which will cause it to overheat and open the thermal fuse. The latter can be replaced with some difficulty and a steady hand. It is normally heat-shrunk and soldered between a mains wire and a thin enamelled copper coil wire.

Try to jump start your fan by pushing it with your hands after starting it. If that doesn't work, then check the fan's wiring- find an electrician, or call the fan's company and check if you still have warranty.

Chances are the bearings are seized. Gently take the motor apart, add wd40 to clean, then add 3in1 oil, if sleeve bearing

eiF ball bearing u could try to regressed them,, but ur best bet is to replace them