My iPod touch won't sync with Bluetooth

You cannot use Bluetooth to synchronise your iPod with your iTunes Library (or anything else). Did you mean Sync using Wi-Fi? To do that, you will need to have previously set up the method in iTunes.

Alternatively, if you mean that the Bluetooth is no longer connecting to a device that you have already paired it with, two things to try:

1. make sure that the device that you are trying to connect to has not connected to a different device. If you have paired the target device (speakers/headphones etc.) with another iPod, iPhone etc. you may have to turn off the Bluetooth on that device so that your iPod Touch will connect instead
2. if the iPod can see the target device, but still not connect to it, then unpair the iPod from the device and pair it up again

If this does not solve your problem, post back with more detail about what you are trying to do.