Don't take it off. Too much of a chance of breaking the tiny retainer ears. You can try to firmly push straight down on the key to get it to reseat. If it will not snap in place, probably will have to send it to HP for a new HP Laptop Keyboard . The new systems have a double retainer with really small tips that actually lock into the back of the key. I have never been able to find the parts and it takes tweezers or really small hemostats to get them in place properly. If only one of the small tips is broken, it will never seat properly. By the way, how about buying a new Laptop Keyboard like Gateway Laptop Keyboard ?
