Liz - I don't think your frogspawn is dead, but once the tiny little tadpoles break out from the jelly substance it gradually dissolves & sinks to the bottom of the pond.. For the first couple of days after hatching the baby tadpoles often don't move about much and then you'll see them increasingly start to wriggle about. Mine hatched about a week ago and are now busy sucking algae on the edge of the pond. If you're worried about them not having enough to eat as they grow you can feed them boiled lettuce leaves (boil for about 8 minutes until the leaf is very limp) and also the smallest quantity of goldfish flaked food.