From truecrypts website:
I forgot my password – is there any way ('backdoor') to recover the files from my TrueCrypt volume?
TrueCrypt does not allow recovery of any encrypted data without knowing the correct password or key. We cannot recover your data because we do not know and cannot determine the password you chose or the key you generated using TrueCrypt. The only way to recover your files is to try to "crack" the password or the key, but it could take thousands or millions of years (depending on the length and quality of the password or keyfiles, on the software/hardware performance, algorithms, and other factors). If you find this hard to believe, consider the fact that even the FBI was not able to decrypt a TrueCrypt volume after a year of trying.
and:
If the TrueCrypt Boot Loader screen does not appear after you start your computer (or if Windows does not boot), the TrueCrypt Boot Loader may be damaged. The TrueCrypt Rescue Disk allows you restore it and thus to regain access to your encrypted system and data (however, note that you will still have to enter the correct password then). In the Rescue Disk screen, select Repair Options > Restore TrueCrypt Boot Loader. Then press 'Y' to confirm the action, remove the Rescue Disk from your CD/DVD drive and restart your computer.
I take this to mean that if you cannot remember the password the rescue disk won't help you. Also you need to create a new rescue disk each time you change your Truecrypt password or you won't be able to access the data.
All I'm really saying is that for whatever encryption mechanism you use, it always makes sense to have a backup strategy that ensures your data won't get lost