To reattach a laptop key that is missing, follow these steps:

1. Gather the appropriate tools: Phillips screwdriver, replacement key, and an adhesive if necessary.
2. Carefully remove the plastic cover under the missing key.
3. Remove the rubber contacts and springs from the missing key area.
4. Place the new key connector into the same slots as the old one.
5. Press the key firmly onto the connector.
6. Screw the plastic cover back on if applicable.
7. Reattach the spring and rubber contacts back into the key area if applicable.
8. Test the repaired key to make sure it functions properly.