The best way to repair Windows 10 is to use the built-in troubleshooters or Startup Repair. To access the troubleshooters, open Settings > Update & Security > Troubleshoot. To access Startup Repair, turn your computer on and off three times. When you see the Windows logo, hold down the power button to turn off your computer. Repeat this process two more times. On the fourth attempt, Windows will boot into the Advanced Startup Options menu. Click Troubleshoot > Advanced options > Startup Repair.