Why wont my iPod touch 3rd generation turn on?

Worst Case: It is bricked and may need to be replaced.

Best Case: It is just a little messed up and needs a little push. Connect it to power via a wall outlet instead of your computer. Try holding the top (wake/sleep) button and the home button for about 10-20 seconds.

Others may have better suggestions.

Either its bricked OR you need to restore it

to restore hold the sleep/wake button and home button til you see all sorts of code

Dont worry its fine!

(Read entire post before trying anything, Not responsible for any damage to your iPod as a result of my post.) Try putting it into DFU Mode and restoring it. If you don't know how to do that Google would be your friend. Also it might already be in DFU mode in that case plug it into your computer with itunes and restore it. Then try jailbreaking again. I'd recomend Spirit or blackra1n or redsn0w. They do a good joob. Also you may have to find a way to downgrade it or Shift click Restore on itunes and pick an older firmware that you previously downloaded

( http://www.felixbruns.de/iPod/firmware/ )and is capable with jailbreaking (3.12 | 3.13)as ios4 isn't compatible. Hope this helps.

P.s. As others have said, jailbreaking voids your warranty and you could be bricked. (Apple disabling your device for tinkering with it. As a result of an unsuccessful jailbreak. Also try using spirit before you restore. ( http://spiritjb.com/ ).

I tried to use limera1n to jailbreak my ipod touch 3rd generation with 4.2.1. I downloaded everything I think. Everything was going just fine but then it stopped in the middle of jailbreaking. The indicator didn't move past the mid mark. Now it won't turn on at all and the computer doesn't recognize it.... it doesn't show up anywhere.... not in itunes, and not in the computer.