I found a Trojan on my Windows PC, but the "Reset this PC" option in Settings wasn't working. I don't currently have a bootable USB installer, although I do have access to a laptop. I'm trying to figure out whether using Windows' local reinstall option and choosing "fully clean the drive" is enough, or whether I need to reinstall Windows from external installation media.
3 Answers
If you’re not ready to wipe the computer, run a full scan with a reputable security tool such as Malwarebytes and Windows Security. However, scanning is not as reliable as a clean reinstall when malware may have had deep system access. Avoid logging into sensitive accounts from the potentially infected PC until it has been cleaned.
If you can’t identify or fully remove the Trojan, the safest approach is to wipe the system and reinstall Windows from trusted installation media. A friend, repair shop, or another trusted computer can help create an installer USB. Afterward, use a separate trusted device to change your important account passwords and enable two-factor authentication, preferably with an authenticator app or security key.
The built-in local reinstall with “fully clean the drive” is more thorough than simply keeping your files, but it may still rely on the recovery files already stored on the computer. If you suspect a serious compromise, an external Windows installer and a complete delete-and-reinstall is more trustworthy. You can create the installer using your laptop or ask a computer shop for help.
So the local reinstall may help, but an external clean installation is the safer option if I’m worried the infection survived?

I used the local Windows reinstall and selected the option to fully clean the drive. Is that enough, or should I still use a USB installer?