I've been banned and I need don't.know why

hello, I've been playing all day today just a normal day, then I log off of my account (ementa1) to log onto my friends account to test out a champ. then I try to log onto ementa1 and it says "your account has been permently banned, I said to myself this must be a glitch so I reopen the client and it says the same thing, also said that Riot has sent an email to me in regards why I've been banned and I haven't received and email also I purchased some rp on that account I'm mad about that, I'm just mad cause I'm unaware why I've been banned please look into this I love your game and I'm so mad to see my account just get banned for no reason please please please help me!