For doing a repair install of Windows 10, follow whichever of the three following instruction sets you prefer. But, definitely download a fresh copy of both the Media Creation Tool and create a fresh copy of the Windows 10 install media using it.
You should never, and I mean never, use an old copy when it comes to Windows 10.
If, by chance, you want to entirely wipe the slate and start completely afresh with Windows 10, then follow these instructions for:
A completely clean install will wipe everything, your user accounts, data, and installed programs so make backups and have installers if you want to put same back on the new installation of Windows 10.
Brian - Windows 10 Home, 64-Bit, Version 1809, Build 17763
Explanations exist; they have existed for all time; there is always a well-known solution to every human problem — neat, plausible, and wrong.
~ H.L. Mencken, AKA The Sage of Baltimore