Why won't it let me press keys to cast spells?

I love league, I haven't had it for too long (about 2 months), and I have been experiencing these issues (i'm specifically talking about the second one I talk about). So i'll have a match that's normal and with players (not bots), and then the game after, I notice that I can't lock my screen. I also notice that I can't press my keys that I use (Q, W, E, and R) to cast my spells (this happens over and over again, I have a normal game then the game after I get these issues. It happens frequently multiple times in a row, too). The problem usually gets fixed with me leaving the match then joining back once or twice, but for the past month, that hasn't been the case. I try leaving and joining, leaving and joining, leaving and joining (and I know some of you will be like "Just play along with it, it's that easy -_-" Well, it's practically IMPOSSIBLE for me to play without a locked camera or being able to just press keys to use my spells). I have to CLICK my spells then use them, and I have to MOVE the screen with my mouse. This makes the game impossible for me to play, and it's like my team is short a teammate. I had to change my key bind for my camera lock, but I just can't seem to find a fix for the spells issue. I searched the web dozens of times, I've looked at all the forums of League, I tinker with it for hours, I can't find anything or get anything to work. If ANYONE has an answer for this, or if ANYONE can suggest anything, please do so. All is appreciated. (and if you wondered, yes I restart my client, I still have the issue, and yes, I even tried uninstalling and re-installing the game, and it doesn't work, and I STILL have the issue. Oh yea, and one more thing. This doesn't happen to ANYONE I know, if you were wondering as well)