Flashing question mark icon
When I open my MacBook Pro there’s a flashing question mark icon. I have followed some advice on Apple Support by selecting Disk Utility but unfortunately the Repair Disk is not lit and therefore cannot be selected. I‘d like to know how to back up files?
Also, how do I reinstall OS X on my MacBook Pro while keeping my files and user settings? Is the OS X Mountain Lion disk normally supplied or can I purchase one? Thank you!
MacBook Pro 13″, OS X 10.10