I HEED HELP WITH THIS MISUNDERSTANDING!!!?

my little sister got yelled at by my dad and I do believe he was being reasonable for why he was angry. My sister got very upset and brought me to the argument. I don't know why she did this but she lied to my dad about me doing all these scandalous things behind his back and that I'm such a mess and blah blah blah. Like he's never heard such things about me he got sad and disappointed. Now he wont talk to me ;'(. I'm hating my sister right now because that was just not fair!!! What can I do to clear out this misunderstanding??? Any suggestions???