Press Command + Shift + .
Open Finder and use the keyboard shortcut again to hide them
In Finder, click Go in the menu bar, then hold Option to reveal Library if needed
Use Terminal and run: defaults write com.apple.finder AppleShowAllFiles -bool true
Restart Finder with: killall Finder
To hide files again, run: defaults write com.apple.finder AppleShowAllFiles -bool false
Restart Finder again with: killall Finder