During the process of preparing the encryption of a system partition/drive, TrueCrypt requires that you create a so-called TrueCrypt Rescue Disk (CD/DVD), which serves the following purposes:
Note that even if you lose your TrueCrypt Rescue Disk and an attacker finds it, he or she will not be able to decrypt the system partition or drive without the correct password.
To boot a TrueCrypt Rescue Disk, insert it into your CD/DVD drive and restart your computer. If the
TrueCrypt Rescue Disk screen does not appear (or if you do not see the ‘Repair Options’ item in the ‘Keyboard Controls’ section of the screen), it is possible that your BIOS is configured to attempt to boot from hard drives before CD/DVD drives. If that is the case, restart your computer, press F2 or Delete (as soon as you see a BIOS start-up screen), and wait until a BIOS configuration screen appears. If no BIOS configuration screen appears, restart (reset) the computer again and start pressing F2 or Delete repeatedly as soon as you restart (reset) the computer. When a BIOS configuration screen appears, configure your BIOS to boot from the CD/DVD drive first (for information on how to do so, please refer to the documentation for your BIOS/motherboard or contact your computer vendor’s technical support team for assistance). Then restart your computer. The TrueCrypt Rescue Disk screen should appear now. Note: In the TrueCrypt Rescue Disk screen, you can select ‘Repair Options’ by pressing F8 on your keyboard.
If your Rescue Disk is damaged, you can create a new one by selecting System > Create Rescue Disk. To find out whether your TrueCrypt Rescue Disk is damaged, insert it into your CD/DVD drive and select System > Verify Rescue Disk.
By Andrew Y. (@andryou) - no affiliation with TrueCrypt - fair use - site for non-monetary, reference purposes only