How do I safely reinstall Windows after a repair shop installed malware?

Create official Windows 11 installation media using Microsoft’s Media Creation Tool on a USB drive. An 8 GB drive is generally the minimum, although 16 GB gives you more room and avoids capacity issues. Boot the laptop from the USB, choose the correct edition—usually Windows 11 Home—and perform a custom installation. Delete the partitions on the replacement SSD only after confirming that anything important is backed up, then install Windows into the resulting unallocated space.

I’d ask the shop for a refund, especially if they installed unauthorized software without your permission. Treat the current installation as untrusted: back up only personal documents after scanning them, and avoid entering passwords or using banking accounts on that system. If you used important passwords there, change them from a separate clean device and enable two-factor authentication where possible.

Windows activation is often stored in the laptop’s firmware or linked to its hardware, so installing the same edition may activate automatically once the computer is online. If prompted for a key, choose “I don’t have a product key” and select the original edition. Office is separate from Windows, so reinstall it only through your legitimate Microsoft account or product license—don’t use cracks or activators.

After the clean install, run Windows Update repeatedly, install drivers only from the laptop manufacturer or Windows Update, and enable Microsoft Defender. If the shop had access to your files or accounts, consider changing those credentials too. Keep the invoice and document the unauthorized software in case you need to dispute the repair charge or report the shop.