When Several Keys on Laptop Keyboard Not Working

I had my laptop on my lap, and as I turned around, the laptop almost dropped to the ground, causing me to grab it by the keyboard to prevent it from falling. I thought everything was okay, until I pressed the "c" key and discovered it didn't work. I took the key off and replaced it. It started working fine.

It was then that I discovered my "a", "z", "q", "1", "`", and "tab" key did not work at all. I tried taking the key off, cleaning underneath, but nothing seems to be working. I turned my computer off overnight, hoping they would start working again, but that was not the case. Is this a problem with the keyboard or an internal problem. I ordered a replacement keyboard (Dell Part: 1M722) but I'm not sure this will help. Does any one happen to know what sort of problem this is and how I would go about fixing it?

But the only other possibility that I can think of other than damaged keys is that your keyboard connector may have been loosened. Keyboards use a matrix to determine if a key has been pressed to they get a signal on a column and on a row. A, encoder chip interprets the signals and send out the equivalent ASCII code. If the encoder is on your motherboard board and not the keyboard module, then the cable could have been partially pulled out, disabling a column or two of keys.

What may have happened is that when you grabbed it, the pressure could have broken a trace (printed wire) on the printed circuit board in the keyboard.  Usually the way a keyboard works is by making a matrix of switches where, for example, "a", "z", "q", "1", "`", and "tab" could be on one column and "z", "x", "c", etc are on one row.  Pushing the "z" key makes a connection between the the corresponding row and column, and the keyboard’s microcontroller interprets that as a keypress on the "z" key.  If you’ve broken the connection to the "qaz" column, the microcontroller will never know that you’ve pressed one of those keys.  Replacing the keyboard will give you a new microcontroller and circuit board, so you should be good to go!

From:Keyboardfast