No jailbreaks work for me?

[Nick]

I have tried Greenpois0n rc6 and that didn't work for me after 10 times and blackra1n and some error occurs like asll or something and I can't fix it because my comp is a price of crap I tried the go to computer settings on c drive and It said nothing helpful so I don't thing limera1n has a 4.2.1 and I don't want to use redsn0w because I heard it's tethered and I want untethered my iPod is 4th generation and version 4.2.1 mc model I think so any help would be great Email me at [email protected] if you have anything to say oh and I just restored it so yea