It’s likely that she’s abandoned the nest site for one a little more private, with less traffic. In all likelihood she’s been off the eggs too long by now to be able to save them. In order to rescue eggs, you would need to create an incubator to simulate the heat from the mother’s body. According to this, the incubation period is three weeks, and the chicks are ready to follow the mother into the water soon after birth. Even if you could hatch the eggs, it’s unlikely that you would be able to teach them the survival skills that they need.