How to reinstall Windows from USB without erasing the wrong drive

Reinstalling can help with damaged system files or persistent software problems. If the system drive keeps disappearing or reports a hardware fault, protect your data and check the drive before writing a new installation to it.

1. Choose a repair install or a clean install

If Windows still starts, open setup.exe from compatible installation media in Windows. Review Change what to keep. If keeping apps and files is important, proceed only when the appropriate option is available. Starting the PC from the USB is the usual path to a clean installation, which can erase everything on the selected drive.

2. Back up and prepare official installation media

Copy personal and work files to another physical drive or cloud storage and open a few files to verify the backup. Save your BitLocker recovery key if applicable, note your licensed Windows edition, and check Windows 11 compatibility. Use Microsoft’s Media Creation Tool and a blank USB drive of at least 8 GB. The tool erases that USB drive.

3. Use the boot menu and identify the target disk

For a clean install, start the computer from the official USB using the manufacturer’s one-time boot menu. Verify the installation target by capacity and the drive layout. Drive letters in Setup may differ from the letters you normally see. If the target is unclear, stop before deleting or formatting partitions. Disconnect the backup drive before you install.

4. Update Windows and restore files

After setup, connect to the internet, run Windows Update and check activation. Download any remaining drivers from the PC or component manufacturer. Test network, display and audio before restoring your files and installing your apps.

Microsoft’s reinstall instructions · Windows 11 requirements