I havent shared any information with any player although this account was originaly from a close person.
Two days ago a player was so angry with me and threatened me so hard. So i wonder if it has anything to do. I tryied to look for his name in my matchhistory but it was already further than 20 games.
Create a support ticket about it and change your password.
If you want to look further pass 20 games, you can check here. Which can be easily found by the drop box if your username on the top right into the match history. You can even find your first ever game with that account there if you really desired to.
https://matchhistory.euw.leagueoflegends.com/en/#match-history/EUW1/239664129
Other than that, I suggest on changing your password of your account to something harder to guess that even your own family can not even guess. Also, send a report on a ticket so if they did anything that may put a ban on your account can be prevented as they know it wasn't you.
