Sometimes you need to see hidden files and folders in your system,
You could use the terminal:
defaults write com.apple.finder AppleShowAllFiles -boolean true
killall Finder
The reverse is
defaults delete com.apple.finder AppleShowAllFiles
killall Finder
Some more explanation here:
http://ianlunn.co.uk/articles/quickly-showhide-hidden-files-mac-os-x-mav...