[GAMEPLAY] Game refuses to acknowledge letter/number keys outside of chat

The last several times I've tried playing League of Legends, a very frustrating bug keeps occurring where my abilities, items, and hotkeys simply refuse to work because they're registered to letter/number keys. Typing works just fine, mind, but abilities themselves refuse to work. Also, going into the controls menu and attempting to bind any control to a letter/number produces no response.

The first instance of this happening was a couple of weeks ago, where I read a suggestion that I delete the .ini file of control configurations, as it was corrupted. This worked well for a while (don't exactly remember how long, or how many games) but then it started happening again!

I've had to resort to testing out my controls in a custom game before I enter an actual match - even then, it doesn't work; my controls worked just fine in a custom game only moments before I actually joined a real game. And when I join a real game, I get very frustrated - I'm not allowed to AFK or leave, so I'm simply forced to basically feed the enemy team by trying to "contribute" without working abilities.

I can work around this, slightly, by using the function keys, but they also offer many hiccups and are obviously not ideal.

Please, assistance? And what should I do if I get stuck in a game where I effectively can't use abilities?

I don't know exactly how to reproduce this - it seems to be a pretty unique problem to me, but I reinstalled the game only a few weeks ago, so that might have something to do with it?

System specs are attached.