How to fix corrupted boot up  

I created the Windows .iso with the Media Creation tool into a 128GB SC in a USB adapter

If you Burned the Windows ISO image to the SD card, then you can attach the SD Card Reader to another computer and view the SD cards contents.
Put the SD Card Reader with the burned ISO of Windows on the SD Card in the troubled computer. Restart and press F12 at bootup continuously. You should be shown a Boot menu with the SD Card as an option. Select that to boot the computer.
If you are still failing to boot the computer with the SD card, then I would use a USB Flash Drive and burn the Windows ISO image using the Media Creation Tool from the same page.

Now what you need to do is to forget trying to use the corrupted Windows installation to do things.

Try booting your PC from a flash drive created with the Media Creation tool.

Then return to post #5.

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The rest is just information/response/explanation- not suggestions.

a/b: Am I correct in believing your win 10 installation is probably corrupted? If so, you might expect things not to work as you'd expect.
Perhaps your not being able to see disks connected to your USB ports is one of those symptoms.

Rather than messing around with the SD adaptor, try plugging in one of your new drives and see if you can see that.

If not, try disk Management.

c:



d. I answered your general question by way of explanation.

You are reading it as if to find a practical solution to what you can't do now.

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" I can't see how a command prompt would help." Your'e saying CMD can't show the contents of USB drives?

No you're misconstruing my answer.

Also, the Windows on the Media Creation Tool, if it's to fix the corrupted files I have, that will be great. However, to do that, I don't want to lose my installed apps or settings, just fix what's corrupted. It has that option, correct?

Not correct. You appear to be expecting a Win 10 install disk to be able to somehow magically fix a random set of problems. It doesn't work like that. It offers a range of possible things you can do e.g.
boot to a command prompt - which is what you should try doing.
+
Startup repair
Possibly System restore
and of course install Windows.

Once booted normally into Windows you can use either a compatible mounted iso file or Win 10 install disk to start an in-place upgrade repair install by running setup.exe.