I messed up my system while trying to fix permission problems for setting up a LAMP local server. I tried this solution: How to avoid using sudo when working in /var/www? without success. Then I saw this solution: Permissions issue: how can Apache access files in my Home directory? I understood that I had to change the permissions of my root directory (among others), so I executed: sudo chmod 710 / I also changed the user group on / to www-data. I also did these operations on /home. I'm pretty sure one of those commands broke something, because it's the last commands I executed, and after that, my system showed strange/broken behavior: Firefox stopped showing pages Some icons got replaced by an red X icon (meaning "Icon not found" I guess) Applications refused to launch (no reaction) After rebooting: I got a strange graphical message talking about not being able to mount something, asking me if I wanted to wait, and talking about /tmp (I forgot the message since I was in shock) My system now boots in console, and when I login, it flashes unsignificant stuff* before re-asking me to login. My important data is on Ubuntu One. I'd prefer not having to reinstall from scratch. Is there a way to regain access to my system? Thanks a lot for your help. *Looks like a terminal header with the name of the OS and other info. Doesn't seem important.