I can't login , return to login screen (it isn't Xauthority)

Question

I spend all day trying to fix the problem but it was impossible. I updated my OS from update manager. I ran a game on steam and the pc has got freeze and then, I rebooted whit button.

When I try to login in login screen, appear one second the desktop, then back to login screen.

I reinstalled the headers, I checked the Xauthority and several other things but anything worked.

I need help!!

EDIT: my OS is Elementary OS Freya. I already tried:

• Check out Xauthority
• Remove Steam and Steam Games
• All this
• sudo apt-get install --install-recommends...
• remove unity-greeter but It is not installed

EDIT 2:

• removed two files

EDIT 3:

• sudo apt-get install --reinstall plank
• sudo apt-get install --reinstall elementary-tweaks
• Installed last graphics drivers from here

EDIT 4:

• VIDEO EXPLAINING ISSUE

Answer 1

Did you try reinstalling Pantheon Desktop?

sudo apt-get install --reinstall elementary-desktop

Or reinstalling pantheon-greeter (you have tried to reinstall lightdm, but it's called pantheon-greeter)

sudo apt-get install --reinstall pantheon-greeter

Answer 2

I added an user and I could join in. Removed elementary-tweaks and numix-icon then I could join again with my user...

I installed again elementary tweaks and it works.

I hope this works for anyone.

Answer 3

I encountered with the same issue. I unfortunately ran earlier that that the

sudo chmod 777 -R .

command in my root directory, which changed all the permission on my computer, included my account. My account permission also change, therefore I was not allowed to log in into my account. Solution: When I ran the command again it solved the problem,I could log in into my account, but it's highly recommended to reinstall the compute for security reasons.