A previous owner, or the vendor, has installed an English version of Windows on your laptop (which would originally have left the factory with a Korean version of Windows pre-installed, together with a recovery partition for the Korean version).
You can't restore the English version because you've overwritten it with the original Korean version.
The only way to get an English version back on it now is to buy an English version of Windows, but even then you will have a problem getting the correct drivers for that model because it's a Korean model which means you would have to get the drivers from that laptop manufacturer's Korean website -- and the website will most likely be written in Korean not English.