You are using a PC that has Windows 10 on it, but it has become corrupted for some reason and while you know that you can repair that using something known as a Repair-Install, -- but you need Wind10 Installation media for an older build (e.g. v19.09) and Microsoft only provides access to the ISO file for the current version of Windows -- v20.04.
So you are out of luck, right?
While MS will not provide you the ISO file you need directly, you can use a tool to BUILD the ISO file from components that MS will download for you -- and you don't even need to know what components are needed.
This tool is known as UUPdump and can be used to download and create Windows installation ISO media. It can be found at this link: https://uupdump.ml/
Once you have that screen open, enter the build number of the Windows version you want into the search box and click on the search icon. You will see that if you enter 18363 (the build number for the 19.09 version) you will get a long list of items, including the most recent build -- which is a lot newer than the original build made back last Autumn.
Scroll down through the list of Builds until you find the one you want and click on it. Since you are most likely running 64-bit Windows, you will want to choose an entry that end with amd74 -- NOT arm64 or x86.
Choose your Language, click the Next button
Choose the edition you want -- the tool will allow you to combine up to four editions into one ISO file. But be aware that the more editions you choose, the larger will be the ISO file that gets created, the more stuff will need to be downloaded, and the longer (in some cases MUCH longer) it will take. Click the Next button.
Select the Download and convert to ISO option by clicking that radio button. Then click the Create download package button. This will save a file to the default saving location for the Browser you are using. The file will be named nnnnn.xxxxx_convert.zip where nnnnn is the Build number you selected.
Create a root level folder on your drive in a location that can hold 10 GB of data. You need that much room because the folder has to hold all the files needed to build the ISO file as well as the resulting ISO file. Make sure the folder name does not have any embedded blanks -- or this tool will not work. Copy the .zip file there and expand its contents into the folder.
You will then see a file named uup_download_windows.cmd
Right-click on that file and select Run as administrator. This will start a process of downloading and running scripts from Microsoft which will then take 30 minutes, 45 minutes, or longer.
When done, you will see an ISO file with a long name in that folder. That is the Windows installation file. You should copy the ISO file to another folder because every time you run UUPDump in this folder, it will overwrite the existing contents, removing the file you just created.
This ISO file is genuine Microsoft stuff -- obtained directly from Microsoft. So, you don't have to worry about any unwanted or third-part materials being embedded in it.
You then go online and download RUFUS, a free utility, that can be used to build a bootable USB stick from the ISO file you downloaded.
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