One thing i want to add, not getting good marks in exam clearly indicates there were some mistakes. For jee main, the mistakes can be not covering 100 percent syllabus, without proper solving questions just ticking the answers in exam, loosing time by attempting difficult questions, going in examination hall with very high expectations...i just want to tell,plz don't bother about past. It will not change. If one is determined, he can do good preparation in one month for jee main. Start with positive mind set,believe in yourself. Make your time table and be punctual. Give a test in 3,4 days. Cover syllabus fully. Don't leave any loops in your study. Talk to one who had scored good marks. Regain your confidence. And don't repeat the same mistakes in april exam. You will score high. All the best!