Most simple thing you should try is to turn off your modem, router, and laptop for two minutes.  Then turn on your modem first and wait until all the lights come up, then turn on the router, then turn on your laptop and try it again.

For powercycling, the modem has to be turned off for at least a minute or two to flush the memory.  If you still cannot access internet, call your ISP and tell them you've done powercycling but still no connection.

한번 그렇게 해보겠습니다...그런데 노트북이 두대인데, 하나는 잘 되고 있습니다.
나머지 한대가 연결이 안되고 있습니다.

If the other laptop has internet connection, then scratch the powercycling idea...