Not being able to login as root
(other than by using sudo
) is normal; Ubuntu doesn't set a password for root
by default.
The empty /etc/sudoers
means you can't use sudo
, of course. But creating a new group shouldn't affect /etc/sudoers
. You must have done something else.
The way to recover from this (short of reinstalling) is to boot into a single-user root shell. From there, you can fix /etc/sudoers
, and whatever else needs fixing. Be careful while you're doing this; it's very easy to break the system by manually editing system files like this and frankly you've already done so.
To get a single-user root shell, see this question. Quick summary: Hold down the left shift key while booting and follow the prompts to get a root shell.
root:x:0
is correct. Have a look at/etc/sudoers
. Should containroot ALL=(ALL:ALL) ALL