Thx for ur help
.This is the first time to jailbreak it. I don't remember using the umbrella thing. For the green letters, it's written: 4.3.5. .. So, what does means
if it was jailbroken before, i was hoping those green letters show up anything between 4.2.1 to 4.3.3.....damn you only have 4.3.5(tethered...which is not terrible at the moment)
TU saves firmwares for restoring/downgrading to a particular firmware that is jailbreakable(and also untethered, which we all prefer), the best one right now is 4.3.3, which you don't have and never will.
4.3.5 is a tethered jailbreak, tethered means, if your device batt dies or you turn it off, you need a computer with a program(redsnow) to be able to start up iPad every time by choosing "boot tethered now".
untethered jailbreak is normal, no computer needed, it boots normally.
now, 4.2.1 might be too old, and tweaks might be too advanced for it, and causing conflicts. So a newer firmware would be good,... your 4.2.1 is untethered though, and if you upgrade you will lose it, as you cannot even save it with TU right now, to downgrade back to it, if you upgrade.
4.3.5 is an option for you, but it is tethered, and you can't go back to 4.2.1.