Postfix accidently removed

Operating system: Ubuntu
OS version: 18.04

Hi, I was following a guide on the internet and it told be to install sendmail, I didn’t pay attention and its installation caused the removal of Postfix. I immediately installed Postfix back, which removed sendmail. But its not working anymore.

systemctl status postfix shows active (exited) status. Running postfix check prints a bunch of warnings

/usr/sbin/postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_client_restrictions
/usr/sbin/postconf: warning: /etc/postfix/master.cf: undefined parameter: mua_helo_restrictions

In the file /var/log/mail.log/ I have

Jul  6 09:58:08 primary postfix/postfix-script[16425]: warning: not owned by group postdrop: /usr/sbin/postqueue
Jul  6 09:58:08 primary postfix/postfix-script[16426]: warning: not owned by group postdrop: /usr/sbin/postdrop
Jul  6 09:58:08 primary postfix/postfix-script[16428]: warning: not set-gid or not owner+group+world executable: /usr/sbin/postqueue
Jul  6 09:58:08 primary postfix/postfix-script[16429]: warning: not set-gid or not owner+group+world executable: /usr/sbin/postdrop
Jul  6 09:58:08 primary postfix/postfix-script[16457]: starting the Postfix mail system
Jul  6 09:58:08 primary postfix/master[16459]: fatal: bind 0.0.0.0 port 25: Address already in use
Jul  6 09:58:09 primary postfix/master[16458]: fatal: daemon initialization failure
Jul  6 09:58:10 primary postfix/postfix-script[16460]: fatal: mail system startup failed
Jul  6 09:58:12 primary postfix/postfix-script[16733]: starting the Postfix mail system
Jul  6 09:58:12 primary postfix/master[16735]: fatal: bind 0.0.0.0 port 25: Address already in use
Jul  6 09:58:13 primary postfix/master[16734]: fatal: daemon initialization failure
Jul  6 09:58:14 primary postfix/postfix-script[16746]: fatal: mail system startup failed

I have a webmin configuration backup that includes the entire /etc/ directory. I also have complete backup of the system on hosting level. But I don’t know how to get back to that state. I’m trying to avoid having to do a complete restore. I tried the backup restore function in Virtualmin, but that gives me following output

Please help.