ASUS with windows 7 need Factory reinstall.

A factory reinstall is nothing to do with Microsoft.

Asus may have imaged a recovery partition on your hard drive to reinstall to as new condition.

See if this works: Asus – Press F9 at Boot to start the process.

If it is not accessible:

You can borrow the exact same edition of Windows 7 Retail DVD and use your Product Key on the COA sticker to reinstall the operating system.

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Or you can use this for preinstalled OEM or Retail Licenses. This is on a first come, first served monthly basis.

Download the correct ISO file and make your own disk and use the Product Key that is on the COA Sticker.

https://www.heidoc.net/joomla/technology-science/microsoft/67-microsoft-windows-and-office-iso-download-tool

Download: Windows ISO Downloader.exe

And here are instructions on how to burn ISO images to disk:

http://www.snapfiles.com/get/ISORecorder.html

You change the Boot Order in the BIOS to be able to boot from your installation media:

How to Boot Your Computer From a Disc or USB Drive

How to access Boot Menu:

https://neosmart.net/wiki/boot-usb-drive/

Then do a clean install:

http://www.sevenforums.com/tutorials/1649-clean-install-windows-7-a.html

The COA sticker is either on the underside of the Laptop or in the Battery Compartment.

With a Desktop it is either on the side, rear or top of the Computer Case.

Using the downloaded ISO file Method may require phone Activation.

It may require that you use phone Activation.

"How to Activate Windows 7 by Phone"

http://www.sevenforums.com/tutorials/18715-activate-windows-7-phone.html

The above method also will require you to go to your Computer Manufacturer's website > Support and Downloads Section > locate your Model Number and Operating System > then download and install the latest Drivers for it.

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Using the USB method in conjunction with the above Windows 7 download:

http://www.sevenforums.com/tutorials/2432-usb-windows-7-installation-key-drive-create.html

"How to Get and Use the Windows 7 USB/DVD Download Tool"

http://www.sevenforums.com/tutorials/31541-windows-7-usb-dvd-download-tool.html

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And this is very good and easy to use:

Rufus - Create bootable USB drives the easy way

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Important: Read about changes to how Windows 7 obtains Updates after a clean install until end of Support in Jan, 2020.

https://support.microsoft.com/en-us/help/4569557/windows-update-sha-1-based-endpoints-discontinued

Cheers.