version `SAMBA_4.11.6_UBUNTU' not found [duplicate]

^{Yes, already posted in the comments as a verified solution, but posting as an answer anyway.}

Purging should indeed remove the configuration files as well, yet the configuration of the Samba server is tracked by the package samba-common, not samba. Yes, it's a bit confusing.

So, try purging and re-installing both packages like this:

sudo apt-get purge samba samba-common
sudo apt-get install samba

If you only need the smb.conf configuration file, there is no need to reinstall samba. The default copy can be found in /usr/share/samba/smb.conf. The following will copy it to /etc/samba/, replacing the file you've been editing:

sudo cp /usr/share/samba/smb.conf /etc/samba/