Have you ever tried to change your user password in a pc with crypted home folder. Well, after doing it you will be not able to access your files anymore cuz your login password now defers from the password to open the ecryptfs of your home directory. Don’t worry! You can easily fix it just doing:

ecryptfs-rewrap-passphrase /home/.ecryptfs/$USER/.ecryptfs/wrapped-passphrase

It will ask for your old password and for the new one. Then just logout and login again and your documents will be decrypted automatically.

So when you change your user password (eg with passwd) remember to run also the command above!