This solution is 100% working, you will not lose any info except the last app or tweak you installed(which caused the problem), so, first turn your Device off, Usually to do so you have to: hold home and power buttons, it will reboot, dont release the buttons, then the screen will go off again, make sure it would not boot again, and release buttons, now it is off, press the power button( to turn it on) and immditly keep holding the VOLUME + Button, it would take a long time, but it is worth it, because you are getting your device back ;D, then it will show a ReSpring-Wheel-Like Wheel, then your device will turn on in "SAFE MODE", go to cydia and then manage, packages, and delete the last tweaks or sources in "manage/sources" that caused the boot loop, and your done!, hope i helped 
, i have posted this because this solution has saved my iPod touch's life, so ehy wont it do to the other one's?, note that your device must be jailbroken :|, again, hope i helped
, i have posted this because this solution has saved my iPod touch's life, so ehy wont it do to the other one's?, note that your device must be jailbroken :|, again, hope i helped