I was writing and testing few python scripts (yes I'm moving lot of stuff from shell / perl to python these days) and accidentally I renamed my own user account from vivek to test. However, I did not noticed change until I rebooted my box. Now I cannot run sudo (or become a root user) and cannot access special devices such as sound or video.
By default your first account has all power via sudo under Ubuntu Linux. There is a special group called adm and admin which grants unlimited power via sudo.
The only solution was to boot computer in emergency mode (reboot computer and at grub menu select recovery mode kernel), open /etc/group file and add user vivek to admin and adm group:
# vi /etc/group
Add user vivek to admin and adm group:
Save and close the file.
Now I'm able to run sudo and do other stuff. Luckily, my scripts always backup critical files before modification. So I was able to restore permission instantly. Here is my group membership with all power and glory ;)
vivek adm dialout cdrom floppy audio dip video plugdev scanner netdev lpadmin powerdev admin