Hi 김부현,
My name is Jen. I am a Windows 10 user like you. Can you still log in to your computer?
If you can still log in, you can reinstall Windows 10 using the Settings in your computer
> Go to Settings
> Select Update and Security
> Click Recovery
> Click Get started under Reset this PC
> Then you will either Keep your files or Remove Everything.
If you are unable to log in to your computer, you can access the Reset Options from the log in screen.
- Click the Power button on the log in screen
- Hold Shift then click Restart at the same time
- Then you will get the "Choose an Option" page
Let me know if you still need further assistance.
Sincerely,
Jen