From the sounds of it, you may have missed something. During a normal LVM gui install, it will ask you twice to enter a password. One for the Root user password, and the other for the encryption password. On boot its the ladder, the encryption password that you will need use.
I would recommend to just try again fresh, and make sure you are following the guide, http://docs.kali.org/installation/ka...d-disk-install hopefully it will get you back up and running.
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