How do I fix my "f" key?

It sounds like it is ether 1 going bad. Or 2 filled. With food and all that gross stuff everyone hates. So, first pull the key off, and make sure it's clean. If your thinking " I never eat at my computer so it's probably clean," still check anyways. Things can build up very easily, and dust also collects. Clean it with chemicals on a rag or a soft, (SLIGHTLY) damp towelette. Just a drop of water or chemicals to prevent damage. Wipe it down then test it with the key back on. If it works then your all good, but if it doesn't work there are other problems. Pull the key off, and press the clear button thing with the laptop on. If it works, your key most likely doesn't fit, so I would suggest ordering a new one and testing it in case the key is cracked, broken etc. it will mess it up. If it doesn't work with the key off, there are many possibilities. I would suggest replacing the mousepad keyboard device. You can either take it in, or, you could replace it yourself. If you choose to do it yourself, you will need to find that part. One you have it you must first, figure out how it is held on. Remove all screws. If it has no screws, locate the tabs on each side, and press them in. Then pull the keyboard off. Be careful not to rip the ribbon wires, connecting to to the motherboard. Then pull those out gentaly, and locate the tabs holding them in. Then, get your new part, and reconnect the ribbon cables. Pop the keyboard back on and then, screw in any screws. Boot your device, and if you did it right the key will operate how it should.

If you have any question, you can ask them or watch a YouTube video.