Different champions

Me and my brother play LoL for a while now (from different account of course) and yesterday when he entered his account and clicked to play a bot game he had exactly my champions. He used Caitlyn (one of the champs i had). I checked his pc and it was his account with his name but with my champions. I said well ok just play.Today i enter LoL and all my champions are just...gone! and i have some random champions which i havent bought or unlocked ( for example i had Caitlyn, Jhin and Vladimir, now i dont have them ) im just left with some random champions that ive never even thought of unlocking. My username is CryptaXD and my brother's is sasheto1999.Please if you have a solution let me know because the champions i have are unplayable for me. Thank you.