How can I change owner back to root? [duplicate]

Solution 1:

Restart the machine, boot into recovery (you should end up being root without having to type in any password). Proceed to chown -R. I think it should work. Report back on how it goes.

Solution 2:

Man, you really did it, all /usr have almost essentials binaries, but lets repair your sudo first:

As root in the recovery console, you should remount the filesystem as read/write first:

chown root:root /usr/bin/sudo
chmod u+s /usr/bin/sudo

Then reboot and try to login, if you get more "Must be suid" errors repeat the process using sudo from the tty:

sudo chmod u+s /path/to/the/binary/you/screwed

Be careful next time and try to use -R --recursive with baby gloves.