When the installation has finished the Mac should automatically restart itself and take you to its Setup Wizard which will ask you a series of questions to guide you through initial setup of your Mac. Click the Continue button and then follow the prompts to reinstall the Mac operating system.

If your Mac is running macOS Sierra or newer then click on Reinstall macOS. Select your Wi-Fi menu and, if needed, enter the password needed to connect to this wireless network.

Click on the Wi-Fi menu icon which appears in the upper right corner of the Mac’s screen.

You’ll be returned to the main OS X Utilities window.

When you have finished erasing the hard drive, click on the Disk Utility menu and select Quit Disk Utility.

You will be warned that everything will be removed from the hard drive and that this is permanent.

Click the Erase button and follow the prompts to erase the hard drive.

It’ll be listed in the left-hand side of the Disk Utility window. Typically the hard drive is named Macintosh HD but yours could have a different name.

Click on your Mac’s internal hard drive.

Click on Disk Utility and then click the Continue button.

When the Mac has completed its startup, you should see a window similar this one:.

Your Mac is now starting up in Recovery Mode.

Once you see the Apple logo appear in the middle of the screen you can release the Command and R keys.

This instructs the computer to startup from the Recovery Partition.

Turn on the Mac and immediately press and hold down both the Command key and the R key.

How to reinstall mac os sierra