Do I need to re-index my Volume?
Open terminal and type:

sudo mdutil -E /



You will be asked for your password, provide it, as this command
requires administrator privileges to run.
After confirming your Spotlight index will be re-built and your files
should appear in the search. ( Depending on the size of your HDD it
can take a while )


To turn Spotlight on/off use:

sudo mdutil -i on /
sudo mdutil -i off /


To fine tune your Spotlight settings open System Preferences > Spotlight



Exclude certain folders from getting indexed: