How to Reinstall OS X Without Losing Data (7 Steps)

Insert the Mac OS X installation disc and restart the computer.
Hold down the 'C' key while the computer is restarting until the Mac OS X installation utility appears.
Click a language from the list, then click 'Continue.'
Click 'Continue' on the 'Welcome' screen.
Click the drive you want the operating system installed to from the 'Select a Destination' screen, then click 'Options.'
Click the 'Archive and Install' option, check the 'Preserve Users and Network Settings' option, and click 'OK.'
Click 'Continue' on the 'Select a Destination' screen, then click 'Install' on the 'Install Summary' screen to begin the installation process.
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