How to Reimage a Computer 

Reimaging is the process of performing a factory reset on a computer, deleting all of the data from its hard drive and returning it to the base operating system. Reimaging makes data nearly impossible to retrieve, so if any data needs to be retained, computer users will have to back it up to an external storage device or cloud.

If a computer’s hard drive isn’t completely overwritten during the erasing and reimaging process, there is a small chance that some remnants of data could remain on the drive, but it’s extremely unlikely.

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Why do people reimage their computers?

If the current operating system gets bogged down with old files and programs and runs more slowly than normal, reimaging can improve computing efficiency. Reasons for reimaging a computer include:

  • Removing viruses or malware
  • Wanting to return the computer to its primary operating system
  • Applying one set disk image to student computers in educational facilities
  • Applying one set disk image to employee computers to either update them regularly or delete a terminated employee’s data

Businesses will often reimage an employee’s computer to eliminate former users’ sensitive data on the hard drive before reassigning the machine.

Reimaging is different from reformatting: reimaging retains the original operating system software, while reformatting removes even those files. If you reformat your computer, you will have to obtain the OS software from a different location and redownload it.

What to do before you reimage your computer

Before you reimage your computer, back up all data that you want to keep. At least one storage medium, such as an external hard drive, is the minimum backup needed, but having copies of data in multiple locations (like a file server and/or a cloud storage account) provides additional security in case one backup source fails.

Before you begin reimaging, plug the machine into an outlet or active power strip so that it doesn’t die during the reimage process.

How to reimage a Windows computer

This overview is for computers with Microsoft Windows 10.

Click the Start button, and then click Settings.

Settings Option in Start on Windows.

Select the Update & Security button.

Recovery Option in Settings Menu, on Windows.

Select Recovery from the menu of options.

Select Recovery on Left Side.

There are multiple choices in the Recovery tab. Under Reset this PC, select Get started.

Recovery Options in Windows.

Select Remove everything.

Reset PC Options Windows—remove everything.

File removal can take from 30 minutes to a few hours. After the file removal has completed, select Continue. You will then see a menu to set up Windows 10 and will be prompted to select your basic settings:

  • Choosing language
  • Choosing computer edition (in this case, Windows 10)
  • Choosing your computer’s architecture

For details from the software provider, see How to refresh, reset, or restore your PC.

How to reimage a Mac computer

To begin the reimaging process, you must navigate to the Disk Recovery menu.

Restart your computer.

As soon as the Apple logo appears on your dark screen, press and hold Option and R. Note that you must do this immediately, or the computer won’t pull up the Disk Recovery menu. You may also use Shift+Option+R or Command+R, depending on your computer.

The Utilities menu will give you four options. Select Disk Utility.

macOS utilities disk utility.

In the Disk Utility menu, select Show All Devices.

Show all devices disk utility Mac.

Choose the correct drive from the menu on the left and select Erase.

Select the system format you want to employ.

Once you have selected Erase, the erasing process will complete.

Once you have returned to the Utilities menu, select Reinstall macOS.

Click Continue.

If you are alerted that you need to connect to Wi-Fi, connect to the correct network.

Agree to terms and licenses.

Select the disk on which you want to install your computer’s current version of macOS.

Installing macOS on Disk.

Once the process has finished, you will receive a notification that says Installation Complete.

Select your country from the list on the Welcome Menu.

Select your Wi-Fi network and log in.

The computer will then ask you to continue through a data and privacy screen, give you the option to transfer data from another Mac, allow you to sign in with your Apple ID, and allow you to create a computer name and account.

For more detailed information on reimaging or resetting Macs, see How to Erase an Intel-based Mac and How to reinstall macOS.

How to reimage a computer with a Linux-based operating system

The computer pictured below is a Dell computer with Ubuntu, a Linux operating system, downloaded on it. These directions can vary between operating systems. To reimage a PC with a Linux OS:

Navigate to the startup splash screen.

Press the key that you need to enter the Bios.

Select your Boot order.

Select the correct device from the menu of options shown. The computer will then check the files within the disk image.

Install the operating system. A window will ask you whether you want to run Ubuntu without installing it or if you want to install it.

Select your language.

Select your Wi-Fi network.

Select Options

Choose Install Now. Click Continue.

You will receive multiple options for reinstalling. If erasing the computer’s drive, choose Wipe Everything and Install from the menu of options. The computer will notify you when installation is complete.

Linux Ubuntu installation complete.

Restart the computer if instructed to do so.

Once the operating system has been installed, it will ask you to select your time zone and your name. After installation is complete, unplug the device from your computer and press Enter.

The software may then give you the option to connect your online accounts to the computer, install updating or patching open source software, install apps, or turn on location services.

Jenna Phipps
Jenna Phipps is a contributor for websites such as Webopedia.com and Enterprise Storage Forum. She writes about information technology security, networking, and data storage. Jenna lives in Nashville, TN.

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