You could give them a few more days.
You could pick up each egg and sniff it. If it smells rotten, it's time to throw it out.
You could look carefully to see if it wiggles, and listen to see if it makes noise. Wiggling or noise means it's alive, but still and quiet could be dead or sleeping, so I wouldn't use that as the only test.
You could candle (shine a bright flashlight through the egg, in a dark room.) If they are alive, the eggshell should be mostly full of a big dark blob, with an aircell at one end, and you might see a beak poking into the air cell or a bit of movement. Movement proves it's alive. Completely still could mean dead or sleeping. But if the chick is much smaller than it shoudl be, it died (quite growing) some time ago.
I would probably look & listen, then sniff and throw out any that stink, then try candling, then leave any "maybe" eggs in the incubator for another two or three days just in case.