I got a ceiling fan with light bulbs in my bedroom. Fan is working fine but light doesn't work. To fix this problem, I bought a wall swich and a pull chain swich to replace them at home depot. However they didn't work for this. I took a look at inside body of fan and found a small back box which looks like a condenser. I suspect that this might be broken and cause this problem, but I am not sure. Could anyone help me for this problem?

The capacitor (black box) doesn't affect the light.

If it is not a remote fan, the only things that can affect the light working are:

1. The wall switch
2. The wiring
3. The pullchain switch
4. The socket(s)
5. The bulb(s).

General ceiling fan troubleshooting and help FAQ- Ceiling Fans N More (http://www.ceiling-fans-n-more.com/ceiling-fan-general-troubleshooting-and-FAQ.php)