My friend was shoplifting and my father is putting the blame on me?

You need to commit yourself to your studies and show with actions that you know you made a mistake. As for your friend you are going to have to let go of that friendship. Even eating lunch with her will continue damaging your reputation. Tell your father you know "now" your friend likes to steal but you will never be like her, and you will start avoiding her. Everybody makes mistakes and you are young and learning. Good luck.