Keyboard failures come in several flavours. If there was an addressing fault in the keyboard switch matrix, a whole row or column (except it's often diagonal) would have died, or all the keyboard would have, same as for a controller failure (but most controller failures have also keyboard LEDs, where present, stop blinking at boot).
A single key could be either a mechanical fault (i.e. something stuck under the key) or an "electrical" fault... using electrical loosely since it might be a capacitive keyboard with no actual electrical contacts from the keys.
A small group of keys that does not fill a row, diagonal or column, as is your case, is in all likelihood a mechanical fault of some kind. It's not guaranteed, nor is it certain that a mechanical fault can be resolved, much less easily resolved (e.g. a water infiltration would be localized, but if the internal PCB has oxidized, there's little that can be done), but the chances are good.
Do the keys have the same "feel" as the others, both tactile and aural? If not, it might indicate something stuck under the keys. Scissorblade keys on some laptops (my old Dell M1330 being the closest example I know) can get slightly off true, and no longer work. Usually, firmly pushing them in position made them work again; but once I had to completely disassemble, clean and remount the "E" key. Removing the key exposed the dome beneath, and pushing the dome resulted on the key being pressed, even if with the key mounted nothing happened. That was how I confirmed it was a mechanical fault.
Try blowing some canned air under the keys. If that does not change anything, try gently prying open one of the keys to expose the dome and see whether it works. A drop of sugared coffee can easily block a group of neighbouring keys (clean gently with a cotton swab and alcohol - isopropyl alcohol if you can get some). If it does not, something bad happened to the switches underneath, possibly moisture causing oxidation.