Please help, my account got hacked

So first off I noticed that my SKT T1 Lee Sin skin was gone, and when I checked my purchased list it said it had been refunded. As I looked more, I saw that all my refunds were gone, while I've only used one. I checked my gifting history, finding that there were 4 mystery gifts to accounts I don't know. They hacked my account somehow, refunded my rp, and gifted themselves. Gifting History. Refund History. These people are NOT my friends and I do NOT know them. If a Rioter would help me somehow I would really like it. You can see the accounts of the hackers on the history obviously, so if anyone can do anything, that would be gr8. Thanks.