DiskWarrior is the essential Mac disk utility.

To make disk that can be booted at startup, open disk utility and highlight "Disk Warrior 4.3 Rev 1107.dmg" in the left window then locate the burn icon on the top toolbar and start the burn. info http://www.alsoft.com/diskwarrior/

"DiskWarrior DVD revision 1107 was released to start up the new MacBook Pros (introduced February 24, 2011) and the new iMacs (introduced May 3, 2011). Some newer iMacs with wireless keyboards have timing issues when starting up from any DVD. Instead of pressing the "C" key immediately upon start up, wait for the startup chime and then press the "Option" key. This will bring up the Startup Manager which will allow you to choose the DVD as a startup disk. If your wireless mouse is not working in the Startup Manager, use the arrow keys to choose the DVD, then press the "Return" key to continue starting up." (alsoft site)

Everything just disappeared after your Mac went haywire. All your work documents. The music you most enjoy. The movie of your kid's first steps. It's your life and it's gone. Don't panic! DiskWarrior will find your documents, photos, music and any other files when disaster strikes and things go missing. Perhaps you've tried to open a document and all that happens is a color wheel that spins and spins and spins? Or when your Mac starts up, all you get is a blinking question mark? Or you were in the middle of editing a movie and now your external hard disk isn't on the desktop? Or your MP3s won't play... Or every time you look through your photos, your Mac crashes. DiskWarrior gets you back up and running fast!