For those of you who have encountered a worrying music-related bug on your iPhone or iPod Touch after updating to the recently released iOS 4.2, we have a few steps which may help you to solve your problem.
As reported from Apple Insider, a select number of iPhone and iPod Touch users have been complaining that their entire iTunes music library had been whiped after installing the iOS 4.2 update on their device.
If this has happened to you, you’ll be pleased to know that there is a quick fix which should correct the problem for you. Firstly, you’ll need to connect your device to iTunes via USB. Afterwards, play a song on the iPhone itself from iTunes and then Click the “Sync” button to re-sync the iPhone. Finally, opening the iPod application on the iPhone to rebuild the music library should fix up the problem for you.
If it works for you, then you should thank Apple forum member “slouchsock8” for the tips. If you have any other problems on iOS 4.2 after updating, you can visit our problem thread here.