Hi:
Using another Windows PC, you can reinstall W10 for free by making bootable installation media using the media creation tool at the link below.
https://www.microsoft.com/en-us/software-download/windows10
If you are asked to enter a product key, select the 'I don't have a product key' option.
To recover your files, when you get to the part of the installation that asks 'Where do you want to install Windows, install it over the current Windows partition, and it will create a Windows.old folder.
Do not delete or format any partitions.
After W10 has completed installing, you can explore the Windows.old folder, find you old user profile and copy any files from there to a portable hard drive for safekeeping.
If you plan on keeping the PC, copy your user profile folders from the old user profile to the new one.
Once you are sure you have everything you wanted, you can delete the Windows.old folder by running the disk cleanup utility.
When you get to the disk cleanup window, click on the cleanup system files button on the lower left side of the window.
The program will run again, and when the disk cleanup window reappears, check all of the boxes to delete the files.
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