Hello, I have got an iPhone 4 with iOS4.2.1 and a few days ago I decided to (tethered)jailbreak it using redsn0w 0.9.6b6... However, since then it has developed a fault with the mic where nobody can hear me. I decided to uninstall the jailbreak by going to iTunes and clicking restore as a lot of forums have advised. iTunes then proceeds to extract the files but when it gets to the verifying part it wont do it. It says it has encountered an unknown error and thats it. I was planning on taking my phone back to the shop and swapping for another as im still under warranty but I need the jailbreak to be gone. I have read somewhere that putting it into DFU mode could help but I have to boot using pc so I don't know if this is possible. when I installed cydia I did click on the 'make my life easier' option. please help me! pleeeeaaase!