I use to work on ubuntu server for Odoo10e and following are few commands which i usually use.

sudo service odoo stop
sudo service odoo start
sudo service odoo status
sudo service odoo restart

I install pysftp using CLI and then executed command sudo service odoo restart but now i am seeing Service Unavailable when i try to access it from url. But when i try to get info from CLI sudo service odoo status is showing following result.

● odoo.service - LSB: Start odoo daemon at boot time
Loaded: loaded (/etc/init.d/odoo; bad; vendor preset: enabled)
 Active: active (exited) since Wed 2018-07-25 13:07:41 UTC; 7min ago
  Docs: man:systemd-sysv-generator(8)
    Tasks: 0
   Memory: 0B
     CPU: 0

Jul 25 13:07:41 ip-10-10-0-84 systemd[1]: Starting LSB: Start odoo daemon at boot time...
Jul 25 13:07:41 ip-10-10-0-84 odoo[3070]: Starting odoo: ok
Jul 25 13:07:41 ip-10-10-0-84 systemd[1]: Started LSB: Start odoo daemon at boot time.
Jul 25 13:15:04 ip-10-10-0-84 systemd[1]: Started LSB: Start odoo daemon at boot time.