Get an installation media that can be any device from CD-DVD, USB, Mass Media, Network.
Plug that in your device.
Reboot the device and from the boot device menu select the option from which you are booting.
A box would appear after some time.
Enter date time and region.
Install now.
Accept the agreement.
Now the tricky part- Custom or upgrade
If you want to erase your C drive and install every program again then go with Custom. Caution this also removes your photos, videos, documents, downloads, and everything on your desktop so make sure you have a backup.
Remember what size your C drive size was or generally, it is Drive 0 Partition 0.
Format it and then continue.
If you choose to upgrade then it is simple nothing would be formatted.
Now it would ask for a product key which you can click skip for now.
Then sit back and relax this would take some time to install new windows.
After it has installed make sure you get your copy registered otherwise it will keep a watermark on your desktop and all your apps and you cannot customize it.
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