Requirement: The hard drive not working and you want to replace the hard drive and restore OS X from internet.
What you need 需要工具：
Screwdriver #00 and T6 螺丝刀 #00 & T6
Details Steps 详细步骤：
To start your computer from Recovery, restart your Mac and hold down the Command and R keys at startup.
开机时按 Command + R 以开始系统恢复。
Reinstalling OS X using Recovery requires broadband access to the Internet using a Wi-Fi or Ethernet connection.
OS X is downloaded over the Internet from Apple when OS X Recovery is used for reinstallation. You must use DHCP on your Wi-Fi or Ethernet network to reinstall OS X using OS X Recovery.
If you bought OS X from the Mac App Store, you may be prompted to enter the Apple ID and password you used to purchase OS X.
After got internet access, set up the new system following the wizards, it may take hours to download and restore the OS.
More details： https://support.apple.com/en-us/HT201314
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