Need more proper light. Put them in the garden during the day, take them in at night.

Possibly too hot if they are shrivelling. I have lost a tray of seedlings in the greenhouse for that reason. But as Owd says they need more light to stop them 'stretching'.

Many thanks i will do as suggested

I reckon you might have to start again with some of them.
But nasturtiums grow very well sown in the ground a bit later in the spring so if you don't have enough light in the house just wait a few weeks. .

Nasturtiums come from the Andes mountains, originally, so you don't really need to wait for the last frost to plant them.