In this case, the only option is to use another computer to create a bootable USB with the Windows installation and perform a custom installation of Windows.
As long as you do not format the C: drive in the Setup, you will not lose your data, but they will be moved to another location. After the installation, you can find a folder Windows.old in the root directory of C: drive. All your files are saved there.
Note: This procedure only will keep the personal files, all software and apps need to be reinstalled.
1-Create a USB device with an installation image.
You can create using the media creation tool, download it on this link.
https://www.microsoft.com/en-us/software-downlo...
2-Enter on BIOS/UEFI and change to boot from the USB device.
3-Click "Install Now".
4- Type your product key or skip it. Usually, your computer will be activated automatically when it's connected to a network if you install the same version of Windows as before.
5- Select the installation type "Custom".
6- Select the C: drive and click Next to proceed. Then, wait patiently until the installation is complete 100%.