Hook your MacBook up to an external monitor. If it works your problem is most likely the inverter and/or the inverter cable. Please give the last three letters of your serial number to determine EXACTLY which MacBook you have so we can direct you to the correct part.
Here's how I replace it: [guide|3631]
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This is the most likely part: http://www.ifixit.com/MacBook-Parts/MacBook-Display-Inverter/IF186-038?utm_source=ifixit_guide&utm_medium=guide_intro&utm_content=required_items&utm_term=macbook_core_2_duo
Hook your MacBook up to an external monitor. If it works your problem is most likely the inverter and/or the inverter cable. Please give the last three letters of your serial number to determine EXACTLY which MacBook you have so we can direct you to the correct part.
Here's how I replace it: [guide|3631]