On the sign-in screen, choose Sign-in options and select the password (key) icon. If the PIN fails but the password works, you can reset the PIN afterwards under Settings > Accounts > Sign-in options.
Use “I forgot my password” or “I forgot my PIN”. Click it below the sign-in box. Microsoft will verify you with a code sent to your recovery email or phone, and then you can set a new one. If that fails, reset the password from another device at account.live.com/password/reset, then sign in on the Surface while it’s online.
If none of that works, hold Shift and click Restart from the sign-in screen, then go to Troubleshoot > Reset this PC. This erases local files, so only do it as a last resort. If the device asks for a BitLocker recovery key, you can find it at