If re-installing Windows does not fix the issue, then I would also say try replacing the keyboard. Should be able to return it if it doesn't resolve the issue.
Can you try another keyboard?
Just to be sure this isn't related to the keyboard somehow?
The fact that it starts after unplugging it and plugging it back in seems to indicate that it isn't loading the drivers correctly.
You could try going into Device Manager and uninstalling the keyboard.
The keyboard will stop working at that point.
Then reboot, this will force Windows to reinstall and reconfigure the keyboard.
sorry for taking so long to respond but i still haven't been able to fix. i have tried everything and i also tried uninstalling and restarting.
this also happens if i put the computer to sleep. sometimes i get very lucky and the numpad light is off when windows starts and i don't have to go and unplug. but for the majority of the times when windows restarts or i turn off the computer the numpad light is on most of the time when it boots which means i have to go and unplug.
this is really getting to be a pain as i hate having to go under my desk all the time just to unplug and replug to get it working properly.
i usually leave my computer on 24/7 for this very reason so i don't have to go and unplug every day. but i end up paying a higher electric bill as a result and slowly killing my desktop everytime i leave it on when i shouldn't be leaving it on.
Reinstalling Windows won't fix it either because ever since i built my pc, i have reinstalled windows multiple times (did a reinstall about two weeks ago) and the problem is always there.
If re-installing Windows does not fix the issue, then I would also say try replacing the keyboard. Should be able to return it if it doesn't resolve the issue.
Not a very elegant solution but you could get a USB Extension Cable and put one end someplace where you can reach it from where you are sitting, i.e. Velcro it to the edge of your desk.
Then at least when it happens you could just unplug it and plug it in again without getting up from your chair.
As to what's causing it, I don't really know since it works and then doesn't, it sounds like Windows just isn't loading the service or drivers when it comes back online, and replugging it prompts is to do so.
I've had things that did this in the past, mainly my 3D Vision infrared emitter.
Fortunately it is right under my monitor and has a plug on its back side.