故 is built from the 古 and 夂 (going / winter (top)) components.
It reads コ like 古, as do 個, 固, 居, and 湖 — learn 古 once and the family's reading comes with it.
A common word using 故 is 故障 (こしょうする), meaning “breakdown”.
Don't confuse it with 枯, 固, 個, and 湖.
