Changed password - now can't login to my account (full disk encyption + encrypted home folder)

So I'm running Ubuntu 15.10. I have full disk encryption setup and an encrypted home folder, I realize this is stupid but I didn't realize what I choose when I set it up and never bothered to try and change it.

So yesterday, via terminal I changed my account + root password. I then tried to start the computer this morning, I get to the account login page, I try to login...it flashes and then goes back to the login page. I understand this is because my home folder can not be decrypted.

I found some guides on line to handle this [ can't log in after password change (ecryptfs) ] however, I can't boot into linux because of the full disk encryption.

I have all password (old + new) and I have the long string passphrase (that I think goes with the full disk encryption).

I really would appreciate your help. I have really important information on this laptop and I haven't backed up in a couple months.

For completeness' sake, I post the solution we found during our conversation in the comments section as an answer:

First of all, you are probably able to boot into your Linux system, you may just not be able to log in graphically, since graphical login usually tries to read/write in your home directory. You can still try to log in using a virtual console (Ctrl + Alt + F1) and work from there.

Using a Live CD instead should also work. You can mount your encrypted system partition from the Live CD, too. For example, you can run gnome-disk-utility on your Live CD and decrypt+mount your system partition from there graphically.

Also, watch out that the instructions in the linked tutorial assume that you are logged in as the user whose home you want to rescue. If you are logged in as another user (e.g. root), then replace the command

ecryptfs-rewrap-passphrase ~/.ecryptfs/wrapped-passphrase

by something like

ecryptfs-rewrap-passphrase /home/[the-user-you-whose-home-you-want-to-rewrap]/.ecryptfs/wrapped-passphrase

or (on a Live CD) by something like

ecryptfs-rewrap-passphrase /[wherever-you-temporarily-mounted-the-home-partition]/[the-user-you-whose-home-you-want-to-rewrap]/.ecryptfs/wrapped-passphrase