Unable to start sshd

Try purging before install:

sudo apt-get purge openssh-server
sudo apt-get install openssh-server

Ubuntu ssh service will start with ssh, not sshd.

Try:

 sudo apt-get remove --purge openssh-server
 sudo apt-get install openssh-server

Then try:

sudo service ssh restart   

To check its status:

sudo service ssh status

Config file can be found at /etc/init/ssh.conf

Detail about remove and purge:

remove - Does NOT remove including configuration files

purge - With Purge command, the configuration files are also deleted.