Erase and reinstall OS X Mavericks
Erase your Mac, then reinstall OS X using the built-in recovery disk. Before you erase, back up your essential files. If you’re installing on a portable computer, make sure your power adapter is plugged in.
Important: To reinstall OS X, you must be connected to the Internet.
- Choose Apple menu > Restart. Once your Mac restarts (and the gray screen appears), hold down the Command (⌘) and R keys.
- If you’re not connected to the Internet, choose a network from the Wi-Fi menu (in the top-right corner of the screen).
- Select Disk Utility, then click Continue.
- Select your startup disk on the left, then click the Erase tab.
- Choose Mac OS Extended (Journaled) from the Format menu, enter a name, then click Erase.
- After the disk is erased, choose Disk Utility > Quit Disk Utility.
- Select Reinstall OS X, click Continue, then follow the onscreen instructions.