We really need more info about which flights you were booked on to provide any advice. Sounds like you are on the Korean Air ORD-ICN flight which operates 5 times weekly in June. All the airlines have made very significant cuts to their June schedules over the last two weekends due to the large dropoff in the travel demand. They did the same thing to their May schedules back in April. If there are no longer any morning flights from your origin to ORD, Delta could put you on a flight to ORD the day before your flight to ICN. There are also daily flights to ICN from DTW on Delta which depart at 2PM. Delta will switch flights for you at no charge.