Apple Mac computers are reliable machines but in rare circumstances you may need to reinstall the operating system.
Fortunately OS X comes with an emergency repair system called OS X Recovery (available on all Macs running OS X 10.7 Lion or Later). In OS X Recovery mode you connect the Mac to the internet and download the OS X operating system. This enables a Mac to restore OS X without needing the installation disks (which is handy, as most Mac computers don't come with optical drives any more).
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How to reinstall Mac OS X: What can I do with Mac OS X Recovery mode?
You can do more than just install Mac OS X using Recovery mode. The Apple support website lists four possible uses for OS X Recovery:
- Restore your Mac from a Time Machine backup.
- Verify and repair connected drives using Disk Utility.
- Check your internet connection or get help online using Safari.
- Install or reinstall OS X.
In this feature we are going to look at how to use Internet Recovery mode to reinstall OS X on your Mac, but if you're troubleshooting a broken Mac it's worth using Disk Utility to see if you can fix the problem first.
How to reinstall Mac OS X: How to access OS X Recovery mode
You access recovery mode by holding down the Command (Cmd, also known as the Apple key) and R keys during startup. Follow these steps to boot into OS X Recovery:
- Make sure you're located near a Wi-Fi point or are connected to a network with an internet connection. (It's best not to use public Wi-Fi for this; try to be at home or on a work network.)
- Turn off the Mac by going to Apple > Shut Down. If OS X is not responding, press and hold the power button until the Mac switches off.
- Wait for 30 seconds.
- Press the power button to switch the Mac back on.
- Hold both the Command and R keys on the keyboard until you hear the chime noise.
The Mac will now start in OS X Recovery mode.
How to reinstall Mac OS X: How to connect to the internet in OS X Recovery mode
To reinstall Mac OS X using Recovery mode you have to connect to the internet. Follow these steps to connect to the internet in OS X Recovery mode:
- Click the Wi-Fi menu in the upper-right corner of the screen.
- Select a Wi-Fi network.
- Enter the Wi-Fi password (if required).
OS X Recovery mode should now be connected to the internet and can download the OS X installation software.
How to reinstall Mac OS X: How to reinstall OS X using Recovery mode
You will now be able to download OS X and reinstall it on your Mac. Note that it is a large file and will take a while to download. The speed of this process is of course dependent on your broadband connection: it's unadvisable to download OS X using a non-broadband connection. You will also need your Apple ID and password to install OS X from the App Store.
Click Install Mac OS X and Continue in the OS X Utilities section of the screen to begin the installation process. Follow the on-screen instructions to reinstall OS X.