How come some of the application components in Photoshop are missing?

How come some of the application components in Photoshop are missing?
I tried to launch Adobe Photoshop application pretty well, but the error has rightly appeared.

Adobe Photoshop
Some of the application components are
missing from the Application directory,
Please reinstall the application.
OK
What must I do to resolve this? I badly need this in making my projects but if I can’t find a way to this, I really don’t know of other best options to do.
Can you please tell me if there is?
Or do I have to reinstall it?
