Keyboard not working! Help needed!

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So I have this Asus laptop. One day a few keys suddenly stopped working. I tried restarting, shutting down and turning it back on, and even restoring it but the keys still wouldn't work. The keys that didn't work that time were C,B, and S. There were probably more that didn't work. No, no liquid spilled on the keyboard. I'm sure about that. But that's not all. I finally decided to get a USB keyboard to plug into my laptop and use it instead of the built-in keyboard. It worked for a while without any problems. After a few weeks, it started acting weird. Some keys didn't work and sometimes certain keys would stick.. not physically. So I tried plugging back the original keyboard.. It worked fine... for a few days. So that was how things went for a few months. This keyboard, that keyboard, this keyboard, whatever worked at the time. Right now the USB keyboard doesn't work at all.. but it does work on different laptops.. and when I plug the original keyboard, some keys are active.. F1. and sometimes the keys C,B,S,O,U and more don't work. What I think is that it has something to do with the computers brain. I don't think the problem is with the keyboards themselves. How do I get to the computers brain and tell it to maybe reset the keyboard input or something? Please help!