LinuxQuestions.org - Cant Login with Gnome (Permissions Error)

Before logging out of gnome on the terminal. I was chaning some permissions using su. The command I used is the following

Code:

chown username:username * -R /home/username

I that this changed all the permissions in most of the / directories to the username. So I changed it using su to be root only. for the certain files.

Code:

chown root:root * -R /path/to

I first noticed the errors when XMMS wasnt able to play anything. So i tried to log in as su and it kept saying incorrect password.

I then logged out of Gnome. And found out I couldnt log back in even as the normal user as it gave me an error when it was writing data about the session. I then opted to login into failsafe which worked however again had no access to su.

Now is there anything I can do, without reinstalling. A friend said i should use Knoppix and change things that way.

P.S
If its any help at the time I believe I was in the root directory / doing the chown.