Certain keys on my keyboard stopped working

My guess is that you have a finicky connection in your keyboard somewhere. Laptop keyboards typically are flexible and very thin. If there is a broken wire in the module, there is plenty of opportunity for the keyboard to flex and break/restore the connection.

The way most keyboards are built is not to have an individual wire path for each key, but use a grid of wires and determine what key is pressed by associating a key with what amounts to an (x,y) coordinate. Since each row and each column share a wire, if there is a break in it somewhere, it can affect multiple keys at once. Depending on how it is built, it could potentially be a problem localized to one area of the keyboard (as you seem to be experiencing).

To confirm that it is a hardware issue, I would plug in an external keyboard and verify that all the keys work on that even if the laptop keys are not. If that is the case, you may need to replace the keyboard. If you can't send it to the manufacturer to be fixed, you should be able to find a replacement keyboard part online. Replacing a laptop keyboard usually isn't a very difficult task, since they typically will just pop out and pop back in, with few screws to remove, if any.