when My TV has no channel in seoul

My TV channels displayed '신호 없음'.
How can repair?

However, most cable TV settings are similar.
Perhaps there is a menu like below.

The TV will have a "메뉴 menu" setting button.
or the remote control has a "메뉴 menu" under Arrow.
then you can find this."
"채널, channel"
"유선방송, CATV"
"채널 검색, channel search"
"자동 검색, auto search"

then TV can find channels.