Often when people think they've deleted an application, what's really happened is that they deleted its icon from the Dock. In the Finder, select
Go ▹ Applications
from the menu bar, or press the key combination shift-command-A to open the Applications folder. If the application is in that folder, drag it to the Dock (not to the Desktop or anywhere else.) The other Dock icons will move out of the way to make a place for it.