MAKE A USB BOOTABLE DISK JUST WITH A FEW CLICKS!
Download the Lion or Mountain Lion or Mavericks OS X and then install DiskMakerX. It is the safest way to make a USB Bootable Disk of OS X!
Just with a few clicks and a USB minimum 8GB, Select the OS X file (Lion or Mountain Lion or Mavericks OSX) and then select the USB Device that you are going to make a USB Bootable Disk of your Lion or Mountain Lion or Mavericks OS X.
The program will automatically format the USB that you will use and will install in it the OS X you selected. DONE in a few minutes !
Restart your Mac, hold on the option key (ALT) and your USB Disk will be shown!
So here in this step, you can reinstall your OS X or
you can do a clean install the OS X you want.
Check it out yourself, it's very easy to use, no need for tutorials,you don't have to be a pro and that's why I share this to all people.
The developers site with more instructions : http://diskmakerx.com/whats-this/