Q: my apps store is showing as korean language, how do I change it back to english? thanks

Have you checked System Preferences > Language & Region to see that you are set to English?

the following article tells how to change the country setting in the app store:

http://support.apple.com/kb/HT2001

in the bottom right corner there is a pic of a country click on that and should be able to change the country that way.

hope this helps!