How do you reattach a keyboard key on a laptop?

you need to press key back to its position but careful it is a delicate device.

here is steps for that laptop keyboard repair.

Use a small dab of super glue to replace keys that have fallen off. Place a small dab of glue directly on the round part that holds the key in place and lightly press the key down. When the glue dries, you'll be able to use your laptop again.