Account got banned by a hacker

I stopped playing my account for a few days correct? Someone hacked onto my account, plays 8 games of urf on jax, 1 game on kaisa. I get banned because I was using "3rd party software". I was not the person who used hacks on my account. I have proof, this hacker thinks he is smart, he unfriended people on my friends list who i frequently talk to so they couldnt chat with him. My friends can back me on this, they have been unfriended. At the same time my account gets banned for "3rd party software" while the last time i played was around 3 days ago. Idk how this is but if i dont get my account back ill just quit this game. Riot better get my account unbanned.