Facebook's private message features are a convenient way to receive communications from friends that are too long for your Facebook Wall or are meant to be private. Over time, you may delete these messages. Once they are deleted, there are ways to recover Facebook messages, but they are time-sensitive. If you have just deleted a message, it is possible to recover it by returning to the Message section of your profile. If it has been some time since you deleted a message, it is also possible to find the notification email sent to you by Facebook containing the text of the message.
Click the "Messages" option in your Facebook profile.
Click "Undo" in the yellow box that reads "You have just deleted a message."
Open your email client.
Locate all emails sent from Facebook. Facebook emails you every time you receive a message. The text of the message is included in the email. If you cannot undo a message deletion, you can find the text of messages sent to you in your past emails.