Did you buy yours used? The K2's charger is different than the K1's -- the K2 converts from wall to USB charger by removing a wall plug 'tip' from the USB plug. If you bought your used, I can see it getting lost (my big fear). But if you bought it new, it should have come in the box (attached to the USB plug, I believe). If it didn't, you should probably call Amazon.
Nope, it did come with that. I bought it new. Didn't know that was what we were talking about. I thought it was two seperate items...