What I thought would be fairly painless is turning into a nightmare.
Norm, reinstall is not a nightmare...
First thing, for me, is have at least two partitions on the HDD:
C: for the programs (Program files, Windows, etc.)
D: for your data (Documents, Sheets, Configurations, Templates, etc.).
So, when formating C: you start only the programs. Your data will be safe!
It's easy to make a full backup too: programs
or your data