A factory reset wipes all apps, files and settings, returning the phone to its out-of-box state. It fixes persistent software problems and is mandatory before selling a device.
- 1Back up first: Settings → Google → Backup, and copy photos with Google Photos or a cable.
- 2Remove your accounts (Settings → Accounts), this avoids activation-lock friction for the next owner.
- 3Open Settings → System → Reset options → 'Erase all data (factory reset)'.
- 4Confirm with your PIN and wait; the phone restarts by itself into the setup wizard.
- 5Restore your backup during setup, or set the phone up as new for a fresh start.
Tip: If the phone doesn't boot at all, use Recovery Mode instead: power off, hold Power + Volume Up, then choose 'Wipe data/factory reset'.