Since she's a wild duck she's a seasonal layer and not really designed to keep laying one clutch after another. Ensure that she's eating a well balanced diet with sufficient protein and calcium. A layer feed and lots of greens should be sufficient. Wild ducks are excellent mothers and nesting/brooding instincts are very strong. Maybe someone else in your area raises ducks and has some fertile eggs your duck could raise. You could sell or keep the ducklings when they're grown.

Each adult female lives for two weeks and lays eggs off and on.

They do use lead, regardless of laws. Rehabbers deal with this regularly. But Wood ducks are not divers or grazers (like Canada geese), so not sure from what source the lead would come. Possible she was poisoned? Or shot, and made it back to the nest? I don't think sparrows would/could kill even a little duck like a Wood duck. Sad to find that. Dirtgirl, may I make a suggestion, though? I say this every spring and summer, and people hate me for it, but I know you will not. I do not think it's ever a good idea to check bird nests that are accessible to predators, or that do not need to be maintained (like bluebirds). I know there was no indication of traumatic injury (like you would with a raccoon attack), but visiting nests regularly leaves a scent trail for mammal predators (like raccoons and even squirrels) and crows watch and figure out something is doing in there. And I am not at all suggesting that's what happened, but you know your stuff, and I know people will probably follow your example more than mine : ) Anyway, happy spring, and good luck with the W. ducks this year.

Post in the forum below. They can answer all your duck questions, and recommend some good books. Here is a link that might be useful: Duck forum