Couldn't find an official fix for months and gave up. Well days ago i did a restore of 4.2.6 cuz i was having issues with phone. I jailbroke phone with jailbreak me and installed all my old apps except for ibooks. Well today i gave ibooks another go. I downloaded ibooks and this time i didn't sync any of my free books i had. Downloaded a new book and i was amazed it opened. Now my phone feels complete that ibooks is working.