Finder is the application which runs on MAC OS and MAC OS X, responsible for moving files and displays all the contents including you drives, files, folders, CDs , DVDs any many more i.e. a complete view of your system. It is the first software which the user encounters after booting his system on MAC and provides a user interface And if a finder finds nothing that means something is wrong with your operating system.. So if you find nothing displaying on that then may be your OS is corrupted and you need to re install it. This will sort out your problem.
This is the biggest question that would arise when you face such kind of problems. Will my data get lost forever? Answer is definitely no. You can still recovery data.