Banned without playing

Well, I just received an email from riot saying my account was permanently suspended due to detection of third party applications or client modifications. The thing is, I stopped playing lol more than 2 years ago, and I never used any of those. I also played a few games a couple months with some friends and again without any kind of cheats. I already opened a ticket to try and get the account back but I would like to know if someone had the same issue.

Thanks in advance

Update: I realized I can view my match history from here, and what a surprise, someone just played 2 matches a few hours ago. I didn't share my account so I suppose it was hacked, I already changed the password and updated my ticket.

Thanks or the answers!