How do I prove my innocence?

I lost my account for "suspicious behavior" and the player behavior representative told me there is no way to get my account back.

I have invested over 5 years into this game and account. This game means a lot to me, but if a long time player doesn't mean anything to Riot I will have to find a new game to get invested in.

I know that I did not cheat. I would just like to know if there is any way for me to show that I haven't done any wrong.

If anyone has experience with a similar issue, I hope they would be willing to help me out. It feels awful to lose my account for something I didn't do.

edit: I was unbanned as they found out it was indeed an error on their end. Thanks @Princess Bubblegum