Have you given Technical Features rights to users??
If not then give it like this:
To activate the technical features, you have to add access rights to your user. You must edit your current user from the menu Settings > Users. Edit your user (probably admin) and, in the Access Rights tab, check the option Technical Features.
Then, update Modules List menu going to Settings/Modules/Update Modules List
In odoo 9 , they are apps (modules) , click on the option Apps , you will get list of apps that you can install..
https://drive.google.com/file/d/0B5j41T1Hqv1sTnFYSncwRlk3emM/view?usp=drivesdk
http://goo.gl/9hPlFP
Install the ones you want , and there are already filters (installed, Not Installed etc)..
Regarding the technical settings : You have to Activate the Developer Mode for that , and then automatically the technical features will be enabled to the current user ..
https://drive.google.com/file/d/0B5j41T1Hqv1sbnBlVFhnN2Y3Rk0/view?usp=drivesdk (click on About odoo)
https://drive.google.com/file/d/0B5j41T1Hqv1sMmhwa1hOWVRUMU0/view?usp=drivesdk
(Click on "Activate the Developer Mode")
Or Restart Server Throw This One
Go to Menu Start --> Type : Services --> search OpenERP or Odoo Server --> Select line and click on Restart/Start/Stop's buttons above – by @Nilesh Sheliya