I cant use sudo

[nohype]

...
sudoers file ... should be on 440 or something like this.
...

This is correct!
Explanation: sudo is the "owner" of "/etc/sudoers" and allows to the owner (=itself) and to group members only read-access-rights to "/etc/sudoers" when executing sudo and forbids all other access-rights.

FYI: file-access-rights are coded like this:

0400 Allow read by owner.
0200 Allow write by owner.
0020 Allow write by group members.
0040 Allow read by group members.

Adding these codes means that access-rights are granted for the individual rights expressed by the unique summands.

So 0660=660 is the unique sum of 0200,0400,0020,0040 with the obvious rights.
But only 0440=440 being the (unique!) sum of 0400 and 0040 are allowed.

So, change these access-rights accordingly with the chmod-command in root-user mode:

$ su -

and then

# chmod 440 /etc/sudoers.

That's it!

Hth
-nohype