Blackbird Chick Abandoned?

Morning

We noticed Blackbirds building a next and avoided cutting back the ivy it was nesting in - at first we could see the nest and eggs were laid. About 5 days ago we could hear chirping - and mum and dad coming and going. but the last two days we have not seen them and cannot hear anything - by climbing onto my shed you can just see the nest (without disturbing) and there are some fairly large chicks in there - not feathered and moving slightly - but no noise and mum and dad not visiting. Have they been abandoned or do they get left more as they grow and its just we are not seeing the occasional visits...kids are a bit upset they cannot hear them anymore.

Can anyone advise on their habits and what might have happened, cant really get an answer directly to this on searching so have come hear to find some advice/answers....

Thank you