How to reinstall OS X from recovery

How to reinstall OS X from recovery

If have a recent Mac, you can use OS X Recovery to reinstall OS X.

1. Turn on your Mac.
2. Immediately after you hear the startup sound, hold the Command and R keys on your keyboard. 
3. Release the keys after the Apple logo appears.
4. If prompted, select a Wi-Fi network, or connect your Mac to the Internet using an Ethernet cable.
5. After the Recovery menu appears, select the option to Install OS X.
6. Follow the onscreen prompts to select your destination disk and install OS X. 

These steps reinstall the latest version of OS X that you previously had installed on your Mac. If you want to reinstall the version of OS X that came with your Mac, hold Command-Option-R at startup instead. This starts your Mac from Internet Recovery.