Will reinstalling Windows delete my files? Can it be done without losing data?

A full clean install does format the drive, so back up first — always. Windows 10/11's built-in “Reset this PC” option can keep your personal files while removing installed programs, but it's not a substitute for a real backup. When we do a reinstall, data backup always comes first, then a clean Windows install, driver setup, and file migration back — in that order, no exceptions.