So finally after a hours of digging

All PostgreSQL files where damaged and missing and i lost hope of repairing them i don't know what caused that but it has a relation with the accidental reboot of the server.

So i managed to find the main cluster data file for my important database information for the production server in this path

    /var/lib/postgres/11/

and i took a backup from it by zipping the whole folder using this command

    zip -r main.zip main/

then i did a full purge and reinstall for postgres using these commands

    apt-get --purge remove postgresql\*

to remove everything PostgreSQL from your system. Just purging the postgres package isn't enough since it's just an empty meta-package.

Once all PostgreSQL packages have been removed, run:

    rm -r /etc/postgresql/
    rm -r /etc/postgresql-common/
    rm -r /var/lib/postgresql/
    userdel -r postgres
    groupdel postgres

Then i installed postgres with this command to match odoo11

    sudo apt-get install postgresql libpq-dev -y

then creating the ODOO PostgreSQL User

    sudo su - postgres -c "createuser -s odoo" 2> /dev/null || true

Now everything is okay odoo should work fine but you still don't have any database

So to bring back the backup from the cluster folder we took earlier we need to move the zip file to the same directory we took it from which is 

    /var/lib/postgres/11/

but before that you should stop postgres service 

    sudo systemctl stop postgresql

and make sure it has stopped 

    sudo systemctl status postgresql

after that rename the main cluster that postgres uses right now because its empty and we don't need it because we are replacing it with our backed up cluster

    mv /var/lib/postgres/11/main /var/lib/postgres/11/main_old

then move the zip file from where you backed it up to the postgres cluster folder with this command

    mv /backups/main.zip /var/lib/postgres/11/

unzip the folder in the same path by using this command

    unzip -a /var/lib/postgres/11/main.zip

after unzipping the folder give the ownership to your postgres user and group

    chown -R postgres:postgres main

Then you are good to go. Start Postgres service 

    sudo systemctl start postgresql
    sudo systemctl status postgresql

and make sure you also start the main cluster service 

    pg_ctlcluster 11 main start

if you stopped odoo make sure to start it also

    service odoo-server start

Ps: I solved ERR_TOO_MANY_REDIRECTS for the odoo sub-domain by commenting ssl configurations in my odoo.config Apache2 virtual host that lets encrypt updated before and everything got back to where left it before installing lets encrypt.

I guess i will leave it here and won't use ssl in production again till i figure out how to use it in a test server .. thanks for your time i hope my question and answer helps someone in the future