My lovebirds led eggs at once after some time they through them down from then thex do not laying eggs
There can be a lot of reasons for a failed clutch. The parents might be too young and inexperienced. The male needs to be about 18 months old and the female should be 2 years old. Younger birds will breed, but they should not be allowed to because the female is at a higher risk of becoming egg bound and dying, and clutches are more likely to fail due to being infertile or due to the inexperienced, too young birds.
If your birds are old enough and this was their first clutch, then it is very common for the first clutch to fail. Some pairs will need several clutches before they have success. And some birds simply do not make good breeders.
A pair that has been allowed to have too many clutches will become over bred, and are more likely to have failed clutches or weak chicks. Be sure to remove the nest box between each clutch and rest the parents for a few months. I recommend a 6 month rest if they hatched chicks. If the eggs were discarded like yours, rest them for a few weeks and then give the nest box back to them.
Thank you for asking Lafeber,