Giant african land snail is dead?

Answer 1

They are proberly in their shells either the temperature isn't right, or the tank too  wet or not wet enough. Break open the seal that is there carefully, and just spray water at their flesh, they should start moving about. Give them food, then every other day  spray the tank with tepid water.

Answer 2

I have two snails and they have not eaten or moved for over a week. When I pick them up I can see that they are deep within their shells with a cloudy film over the opening. Are they in hibernation or dead?