Hi petermurch you don't think any caustic fluids ie bleach etc could have been put in mistakenly with the kitchen waste, Roy.

Kitchen waste and green leaf compost can become very acid, enough to stress the worms. The usual advice is to add a little garden lime to each addition of material.
Also adding shredded paper is a good way to get a Nitrogen to Carbon balance in the compost. Excess nitrogen becomes ammonia in the acid and poorly aerated conditions and that will also kill the worms.

If I am adding a lot of green stuff to the compost I put some garden soil in with it. Green waste on it's own forms a soggy matt and prevents aeration.

Thanks for the replies.Bleach not an option.Already put shredded paper and cardboard in . So will try the layer of earth. Still I suppose the worms will become compost.First time in 50 Years I have seen this happen