Permanant Banned Account... But I havnt played in almost a year?

Hello, so I've been playing LoL since I was season 3, but I felt that the game lost a lot of the zeal and interest that kept me coming back to the game over and over again. I decided to try and play again earlier this week to find that I'm permanently banned due to being toxic. I don't understand who could have gotten into my account. This is an incredibly valuable account that I have used to enjoy this game for a very long amount of time. During my time in the game, I was never reprimanded or disciplined for toxicity or any sort of player misconduct. Is there anyway for this issue to be fixed????