lost my skins and lost rp how do i change password

I was over at my friends house and when i got back he came over and so i didn't want to play league with him at my house. So when he leaves I get on to play and i see that i don't have my dunk master skin and project zed skin, so i was looking around and I see that i gifted people champions and I have never done that so i was wondering if anyone can tell me how to change my password.