Chosen Solution
This problem started after I reinstalled OS and while downloading the updates, the electricity supply went off and power was cut. The airport card shows ‘yellow’ light and tries to look for networks just for a second but does not detect any network. I have run extended hardware test and it did not show any hardware problem. What could be the problem and how to resolve it so that I can use wifi.
First of all I would recommend creating a new network ‘Location’. This can be done by following the instructions below; Launch “System Preferences” from the Apple menu or Dock Select the “Network” panel Click on the “Location” pull down menu and choose “Edit Locations…” Click on the + plus icon to add a new network location, give it a unique name, and click “Done” This will create a new set of Networking settings. We can also try trashing the Airport plist, this can be found in the following directory; /Library/Preferences/System Configuration/ Delete com.apple.network.plist and com.apple.airport.preferences.plist You may need to enable the Library since you are using OSX Lion, this can be done by typing the following command into the Terminal, found in the Utilities section, chflags nohidden ~/Library/ Send this file to Desktop to keep it safe for now and then restart the Macbook. Now try to find your network. Hope this helps,
Sorry for this big delay in replying as I was travelling. Sorry but nothing mentioned above works. I have snow leopard and not lion. OS 10.6.8. The service center says the problem is with airport card and display. How can that be possible? Can interruption in electricity supply damage the airport card and display??
