Comment 12 for bug 657900

well for now I restored the sudoers to operate normally by selecting recovery mode when the system is booting up

Then visudo command

And comment out the lines which Smb4k has added for some reason

# /etc/sudoers
#
# This file MUST be edited with the 'visudo' command as root.
#
# See the man page for details on how to write a sudoers file.
#

Defaults env_reset

# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root ALL=(ALL) ALL

# Allow members of group sudo to execute any command
# (Note that later entries override this, so you might need to move
# it further down)
#%sudo ALL=(ALL) ALL

#includedir /etc/sudoers.d

# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL

# Entries for Smb4K users.
# Generated by Smb4K. Please do not modify!
#User_Alias SMB4KUSERS = agent86
#Defaults:SMB4KUSERS env_keep += "PASSWD USER"
#SMB4KUSERS agent86-S2865 = NOPASSWD: /usr/bin/smb4k_kill
#SMB4KUSERS agent86-S2865 = NOPASSWD: /usr/bin/smb4k_umount
#SMB4KUSERS agent86-S2865 = NOPASSWD: /usr/bin/smb4k_mount
# End of Smb4K user entries.

All entries are commented out and the only thing that is not commented are these:

Defaults env_reset
root ALL=(ALL) ALL
%admin ALL=(ALL) ALL

note that smb4k also had changed this line to read:
#
%sudo ALL=(ALL) ALL

which I'm not sure if it should be commented or not so I commented this out until i can figure out how to edit these smb4k lines so that I can actually use the program

Anyhow this won't solve your smb4k troubles but at least will restore you ability to use sudo
I hope this helps