I need my deleted massages from the FaceBook chat log. How do I recover them?
once you delete your messages you can't recover them .
Reading & Deleting Messages
No. Deleting a message permanently removes it from your inbox. If you want to hide a message from your inbox, but not delete it, you can archive it.
the other Friend(s) involved in the conversation will still have the message that you delete, they can email to you