account stolen, then banned :/

I dont generally come to forums, but my attempt to recover my stolen account came back with news that it had been banned for toxic behavior! i took a hiatus from league for a bit, and when i attempted to log back on i couldnt. i sent a request, giving all the needed details to prove i am the original owner of the account. there must be a way to see where this other person was logging in from? there's got to be a way to prove that the person who abused my account wasn't me. any advice?