How to jailbreak itouch 4g after being updated with new itunes software?

[elaine]

I jailbreaked my itouch before but now that i updated it with the new itunes software, i cant jailbreak it again D: I tried limeraIn which I used before and worked but whenever I tried it, the icon never showed on my itouch but it said "done". Which I tried greenpois0n, it never the "ready to jailbreak" icon never lit up but I still clicked "jailbreak". The screen turned white at first, but after watching a youtube tutorial it would have text after the white screen, I didnt get it. And everytime I tried to, it would sent me back to the icon to connect my itouch to itunes. I have 4.2.1 version. HELP PLEASE T-T