I have aMacBook Pro 2009 15" the hard disk doesn't work anymore. Let me explain, I still can turn on the Mac, but the only thing that works is OS X Recovery. I tried everything but I can't format or restore the hard disk. The hard disk still show up in the recovery menu, but I can't do anything, can't even format/restore/ for some reason. So I decided to change hard disk. What will happen after I changed hard disk? Will i still be able to acces to OS X? Do I need to install the Os again? Because I lost the CDs. It's a easy task? From the guide that I saw looks easy, should I try by my self?