Error when I type sudo in the terminal.Also I get an error when I am requested to authentycate do not show the line for the password and instead shows an error message

[MTA]

mt@mt-MS-7728:/usr/lib/sudo$ sudo chmod -R u=rw sudoers.so
sudo: error in /etc/sudo.conf, line 0 while loading plugin "sudoers_policy"
sudo: /usr/lib/sudo/sudoers.so must be only be writable by owner
sudo: fatal error, unable to load plugins
mt@mt-MS-7728:/usr/lib/sudo$ chmod -R u=rw sudoers.so
chmod: changing permissions of 'sudoers.so': Operation not permitted
mt@mt-MS-7728:/usr/lib/sudo$ pkexec chmod go-w /usr/lib/sudo/sudoers.so
Error executing command as another user: Request dismissed
mt@mt-MS-7728:/usr/lib/sudo$ mount -o remount,rw /
mount: only root can use "--options" option
mt@mt-MS-7728:/usr/lib/sudo$ mount --options remount,rw /
mount: only root can use "--options" option
mt@mt-MS-7728:/usr/lib/sudo$ chmod 644 /usr/lib/sudo/sudoers.so
chmod: changing permissions of '/usr/lib/sudo/sudoers.so': Operation not permitted
mt@mt-MS-7728:/usr/lib/sudo$ chown root:root /usr/lib/sudo/sudoers.so
chown: changing ownership of '/usr/lib/sudo/sudoers.so': Operation not permitted
mt@mt-MS-7728:/usr/lib/sudo$ cd ..
mt@mt-MS-7728:/usr/lib$ cd policykit-1
mt@mt-MS-7728:/usr/lib/policykit-1$ ls -l
total 32
-rwxrwxrwx 1 root root 14328 mar 27 2019 polkit-agent-helper-1
-rwxrwxrwx 1 root root 14552 mar 27 2019 polkitd
mt@mt-MS-7728:/usr/lib/policykit-1$ sudo chmod -R u=rw polkit-agent-helper-1
sudo: error in /etc/sudo.conf, line 0 while loading plugin "sudoers_policy"
sudo: /usr/lib/sudo/sudoers.so must be only be writable by owner
sudo: fatal error, unable to load plugins
mt@mt-MS-7728:/usr/lib/policykit-1$ chmod -R u=rw polkit-agent-helper-1
chmod: changing permissions of 'polkit-agent-helper-1': Operation not permitted
mt@mt-MS-7728:/usr/lib/policykit-1$
Ubuntu 18.04.5 LTSmt@mt-MS-7728:/$ xprop WM_CLASS
WM_CLASS(STRING) = "gnome-terminal-server", "Gnome-terminal"
mt@mt-MS-7728:/$ locate -b "\gnome-terminal-server"
/usr/lib/gnome-terminal/gnome-terminal-server
mt@mt-MS-7728:/

I expected it to work normal giving me root access to the commands.

It gave me an error message that says"sudoers.so"must be writeable only by the user and actually it is set up to be read and write for all,that was my mistake when I ran a chmod 777 for the whole lib directory since then sudo does not work and now when I try to chmod without sudo it says,permission denied and when I try with sudo it gives me the error,so it is a circle I can not get out of.Another problem I have,probably,from the same origin,is the authentication label that do not show the line where the password should be inserted and instead it shows an error message that says something about the /usr/lib/policykit being restored to its original state.Well this is all I have to say ,for the moment. Thanks.Please see if you can help me.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: evince 3.28.4-0ubuntu1.2
ProcVersionSignature: Ubuntu 5.4.0-54.60~18.04.1-generic 5.4.65
Uname: Linux 5.4.0-54-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.20
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 20 20:48:22 2020
InstallationDate: Installed on 2020-11-16 (4 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
SourcePackage: evince
UpgradeStatus: No upgrade log present (probably fresh install)

[MTA (martoyu)]

I need the authentication screen in order to use the synaptic package manager and the ubuntu software which I can not access by now and I can not install any new applications because they ask me for my password; I can not send you any screenshots of the authentication pop up because it is modal when it appears and blocks the whole screen,of course,I also need the sudo very badly to do many things I am currently doing.Awaiting for your news. Thanks.

[Sebastien Bacher (seb128)]

Thank you for taking the time to report this issue and helping to make Ubuntu better. Examining the information you have given us, this does not appear to be a bug report so we are closing it and converting it to a question in the support tracker. We understand the difficulties you are facing, but it is better to raise problems you are having in the support tracker at https://answers.launchpad.net/ubuntu if you are uncertain if they are bugs. You can also find help with your problem in the support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://ubuntuforums.org. For help on reporting bugs, see https://help.ubuntu.com/community/ReportingBugs.