Ubuntu 12.04 unable to login. The username appears but the image disappears. Lightdm problem?

view full story

http://askubuntu.com – I have been using Ubuntu 12.04 for some time but recently it has crashed and hen I restarted I cant login. I am unable to move my mouse pointer , cant login , and user name appears but user image doesn't appear in lightdm.. (HowTos)