I have two accounts on my computer: james and john. james is the only administrative account and a few days ago I set it to expire out of curiosity. Now am stuck. I can not login using james because it has expired, I can not use john for anything because it is not a member of sudoers. I can not login as root probably because root and james shared a password.
Just turn off the computer , use another live system , e.g liveCD ,
Boot and chroot , change the password and expire time.
Boot into single user mode.
easiest way is to add "s" to the end of the kernel line in grub (use e to edit the entry, and b to boot). It'll usually drop you to a root prompt.
sharing a password should not matter by the way, so going to james and doing "su" should work.