Welcome to the TH community, Louibelou!
Can you please share more details about your system's configuration? Unfortunately, it's possible that you might be dealing with a faulty hard drive. If you have any important data on it, you should definitely consult a professional data recovery company for assistance with the retrieving of your files.
I'd suggest you check how the HDD boots if you plug it in a different SATA port on your motherboard and using a different SATA cable.
As for Windows, the operating system is tied to the motherboard, so you shouldn't face any issues with the clean install, if you need to replace the HDD. You can easily download the same OS version from the MS website and
create a bootable flash drive with the installation.
Hope this helps. Best of luck & keep me posted!
SuperSoph_WD