[Client] [Crash] League Client not working.

Over the past few days, I have had a recurring problem with my league client. I game on a Windows 10 laptop and, until about three days ago, League worked fine. Now, if I do get on League, it does not show invites and has prevented me from banning and selecting champions, which makes me worry about getting banned. When loading into the game, I am stuck at 0% for a while before suddenly loading in and, despite being in the game, I am consistently hit with lag of ranging severity. Once the game is finished, the game does not take me to the honors screen and instead freezes up, forcing me to close the game, since the "skip waiting for stats" doesn't work. So, I attempt to restart the game. However, when clicking on the League shortcut, the League logo will pop up for a second and then disappear without League ever coming up. I have tried multiple solutions, including (1) troubleshooting the game [which didn't work], and (2) re-dowloading the game. When attempting to do solution (2), it brought up a error message saying "Your League of Legends files are corrupt. A repair will be started to address the issue. If you continue to experience this issue, please contact Player Support." I was prompted to repair it, which ended in the client saying "Repair failed." Once, when I did get League of Legends back running again, I was able to play the game once before these symptoms happened all over again. I really have no idea what to do and if this problem is in League itself, my computer, Windows, or something else. Please help!