They’re all dead. Spider-Man? Dead. Black Panther? Dead. Dr Strange? Dead.
The tl;dr on Avengers: Infinity War is that Thanos is a real bad egg. He collected five infinity stones; the time stone, reality stone, space stone, mind stone and the soul stone. The person using the stone can manipulate whatever the stone is named after.
Thanos then put the stones in a fancy glove and snapped his fingers so half the universe’s population disintegrated. It was heartbreaking but it does mean Infinity War is the one film you should catch up on before you see Endgame.