Make certain that you have a good Internet connection and boot your machine from Apple's servers by holding down the command, option and R keys whilst booting. It will take awhile, but you'll soon see a globe on your screen and you'll finally see the Internet Recovery window:
Select Disk Utility and erase and reformat your drive. Then select "Reinstall Mac OS X" - it will take a while as all of this is going on via the Internet.
Call back if you can't get that far.
Clinton
MacBook Pro (15-inch Late 2011), OS Mavericks 10.9.4, 16GB Crucial RAM, Crucial M500 960GB SSD, 27” Apple Thunderbolt Display