applications do not appear in finder window after upgrading to yosemite

I have a MacBook Pro 13" Retina display purchased in 2011-12. It worked well all along , until I upgraded to Yosemite last year. I open the finder window, see the 'Applications' folder in the sidebar, but with no applications in the folder. So, without panicking , i did a Spotlight Search, say for example 'Photo Booth' . The search shows me the app, also its location. but when i open the file location, nothing's there, IT'S EMPTY. It's the similar process for various Apps, and obviously it's been such a pain.

Basically , all the applications are somewhere in the system, but i am not able to find them even in the Applications window. Please be kind to help me regarding this issue. Thanks .