I jailbroke my ipod and it won't be recognized by my computer so how do I unjailbreak it now?

Un-jailbreaking your iPod Touch means that iTunes must recognize your iPod. Without the recognition, you cannot Restore the iPod (Restoring it 'un-jailbreaks' it). Your warranty is void since you made an unauthorized modification to the iPod (jailbreaking it voids the warranty).

The best you can do to 'un-jailbreak' it is to take it to an Apple Genius to have it restored from there.