If you are careful and treat them well, you can use WD-40 to loosen the grip on each other. It makes them slippery, so repeat application: be careful! This is an easy way to loosen them and not drink from a pile of stuck glasses. Don’t forget to rinse them afterwards.
Picking up your phone from the ground and not knowing what the screen will look like is the most dreaded contemporary situation. It’s like playing a game of roulette. Now you can rest easy knowing that it doesn’t have to look that bad.