cannot login into locked Ubuntu 14.04 session Unity

I cannot login into locked Ubuntu 14.04 session Unity.

Output from /var/log/auth.log:

Apr 18 15:10:45 trusty-1 unix_chkpwd[3171]: check pass; user unknown
Apr 18 15:10:45 trusty-1 unix_chkpwd[3171]: password check failed for user (martin)
Apr 18 15:11:02 trusty-1 dbus[660]: [system] Rejected send message, 2 matched rules; type="method_return", sender=":1.13" (uid=0 pid=1328 comm="lightdm ") interface="(unset)" member="(unset)" error name="(unset)" requested_reply="0" destination=":1.67" (uid=1000 pid=2154 comm="/usr/lib/x86_64-linux-gnu/indicator-session/indica")
Apr 18 15:11:02 trusty-1 lightdm: PAM unable to dlopen(pam_kwallet.so): /lib/security/pam_kwallet.so: cannot open shared object file: No such file or directory
Apr 18 15:11:02 trusty-1 lightdm: PAM adding faulty module: pam_kwallet.so
Apr 18 15:11:02 trusty-1 lightdm: pam_unix(lightdm-greeter:session): session opened for user lightdm by (uid=0)
Apr 18 15:11:02 trusty-1 systemd-logind[871]: New session c5 of user lightdm.
Apr 18 15:11:03 trusty-1 lightdm: PAM unable to dlopen(pam_kwallet.so): /lib/security/pam_kwallet.so: cannot open shared object file: No such file or directory
Apr 18 15:11:03 trusty-1 lightdm: PAM adding faulty module: pam_kwallet.so
Apr 18 15:11:03 trusty-1 lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "martin"
Apr 18 15:11:12 trusty-1 lightdm: pam_unix(lightdm-greeter:session): session closed for user lightdm

I solved by installing libpam-kwallet4 libpam-kwallet5 .

$ sudo apt-cache search kwallet |grep pam
libpam-kwallet4 - KWallet (KDE 4) integration with PAM
libpam-kwallet5 - KWallet (Kf5) integration with PAM
$ sudo apt-get install libpam-kwallet4 libpam-kwallet5
$ sudo service lightdm restart

Your log suggests that there is a problem with /lib/security/pam_kwallet.so. Can you determine if that file still exists, you may have to reload the kwallet:

sudo apt-get purge kwalletmanager
sudo apt-get install kwalletmanager

Rebuild the pam authentication settings. Go to another TTY CTRL-ALT-F1, then run:

sudo pam-auth-update
# Make no changes and select "Ok" to update the config
sudo service lightdm restart