Reset this PC reinstalls Windows. The result depends on whether you choose Keep my files or Remove everything, so check the option before the final confirmation.

Keep my files preserves personal files but removes installed apps and resets many settings. Remove everything removes personal files, apps, and settings from the selected scope. Cloud download obtains Windows files online; Local reinstall uses files already on the PC. Neither choice should be treated as a substitute for an independent backup.
From Windows Recovery Environment, use Troubleshoot > Reset this PC. If the disk is failing or the reset loops, stop retrying writes to the disk and protect your data first.
Back up personal folders to a different physical drive before choosing a reset option. A file backup does not preserve installed Windows applications.
Step 1. Connect a separate backup drive. Open Backup and Recovery and choose File backup.

Step 2. In the folder tree, expand the appropriate drive and select the folders you need to protect. Check game saves, Documents, Pictures, or other locations that matter for this task; do not assume every needed file is in one folder.

Step 3. Choose a destination on another physical drive or a trusted network location. Check its free space and give the task a recognizable name.

Step 4. Click Proceed and wait for the progress screen to finish. Confirm the backup exists, then keep the backup drive separate from the source PC.

Will Keep my files preserve programs? No. Expect to reinstall desktop apps and review settings afterward.
Does reset remove files from every drive? The result depends on the chosen reset scope and settings. Read the final confirmation and disconnect drives not involved.
A reset can keep personal files or remove them, but it still changes apps and settings. Read the final choice and verify a separate backup before starting.