School problems please please please help me?

i am in year 8 and i would love any help i am in a real mess,some guy owed me some money only 90p and he has been saying he would give it me for 5 weeks now so i headed him and he told the teacher she said she was gonna phone my parents but luckily they were at work and she said i have to go home and i luckyly got out of school ok.tommorow i have to go to school avoiding the teacher that said it and the headmaster and my parents not knowing or a lie or excuse or any help what to to please help me