Account was hacked, then banned for 2 weeks

Well to start off I had not been playing league for 2 weeks, although recently I wanted to start playing again because school got out and winter break started. So I logged on and got into champ select...... Then I got a message that kicked me and said I was banned for 14 games for being "toxic" I would do anything to assure that this was not me, I had not been using this account for 2 weeks, and was never this toxic of a person. I understand that riot would not unban me if it was my relative or friend, but if im being hacked, what can I do? Really would be nice to play league for winter holidays again!