Are you getting OS X blue screen on boot ? When you are switching on to the Mac system you are not able to log in as as a blue screen appears which means the operating system can't be loaded and welcome screen is not displayed. The data that is stored in the Mac hard drive can not be accessed which is a case of data loss. You must be eager to know about the reason of the OS X blue screen on boot and how you can get your data back. The cause of Mac blue screen is that either the Mac hard drive is not responding or the Mac OS X is corrupted because of which the Mac OS X is not loading. So to fix OS X blue screen on boot you have to format the Mac hard drive and then re install the latest Mac OS X version and your system will boot again. Now to recover the Mac data you can use the Mac time machine back up utility to restore the files. If the time machine does not work then you can use the Mac data recovery software which can scan the Mac hard drive and show the preview of the files for recovery, Select and restore. You should then download the software when you have fixed OS X blue screen on boot.