What do you do if your laptop key falls off? Well, it doesn’t really fall off – most likely, 
someone ripped it off or you just mistakenly dropped water or some other liquid on it. What are your next steps?
You can attempt to re-attach the key which is only possible as a permanent fix on select laptops. Most laptops make it almost impossible to re-attach and, at best, is a 2-week flimsey fix. For most laptops, you will need to replace the keyboard. The keyboards may be purchased from the manufacturer and most of them are a 4-screw removal job for replacing. Some entail more screw removing, lifting, and prodding, and may be better for a technical support rep to assist.