You cannot re-install just outlook separately to the Office suite on its own . .
Follow these steps to perform a full repair of your Office installation . . .
Open Control Panel - Programs and Features
Click Microsoft Office in the list of installed applications
At the top, click 'Change'
On the resulting dialog, click 'Repair' - choose the Online Repair, it is a comprehensive fix
That should fix any issues with your Office Installation . . .
If the above did not repair your Office installation and indeed Outlook: