iOS 4.2.1 was released last night by Apple and it seems that not everyone had a pleasant experience because some users lost the music from the iPod application in the terminals. The affected terminals include both iPod Touches and iPhone terminals. Fortunately for everyone there is a SOLVING very simple and easy that will bring all your music back to the iPod application. This problem appeared mainly to those who only updated to iOS 4.2.1, so it is not a problem related to jailbreak.
All you have to do is connect the terminal to iTunes, listen to a song from iTunes and then resynchronize everything you have in iTunes with the terminal. iTunes will not synchronize all the music with the terminal but only some files and in this process it will bring all your music back to the iPod application.
Apple seems to have rushed this update for iOS quite a bit and there is a chance that other errors will appear in the near future.
