hold the home and power button at the same time for a few seconds. It will then reset. If that doesn’t work, plug it in to iTunes and restore it. Then jailbreak it again I guess.

If you’re on software version 1.1.4 on your iPod Touch, there is a patch in the Installer App:

Install: Tweaks (1.1.4): YouTube Activator 1.1.4

Use at your own risk! I make no claim to the effectiveness of that patch or any problems that may result. But seeing as you have already voided your warranty, might as well right?...

All else fails, back up/sync iTunes, then do a software Restore in iTunes, then re-sync and then jailbreak again…at least that’s what others suggest on the intertubes…