That kind of sounds like you might have had a swarm. Eggs can be hard to see, they look like tiny grains of rice stuck upright at the bottom center of the cell. Move the frame around at angles to the sun and see what you can see then.
If the old queen swarmed they took a lot of the stores with them and the queen quit laying about a week before the swarm. A virgin queen might not show up for 2 weeks, meantime the remaining brood hatches and the beekeeper goes bonkers thinking he has a queenless hive. If you can put a frame of brood from another hive and see what happens, if they draw queen cells then they did go queenless, if they don't chances are the virgin queen hadn''t started laying at the time of the last check but probably has by the time you recheck the frame of brood so search for signs of eggs and larvae.
It is best to try the frame of brood solution before panicking.