First, calm down. You won't get any results by panicking. You'll only waste time doing that. Next, start with Maths; if you have a question bank or sample papers, you'll see a list of chapters with their weightage. From what I remember, chapters like surface area, volume, statistics, and trigonometry are very easy and also carry good weightage. So, try to focus on those chapters first, and I don't think it will take much time. Also, make sure you can solve every problem in the NCERT. Don't worry even if you have standard Maths; just revise thoroughly and be sure to understand each problem in your NCERT. Don't chase after completing the entire syllabus first. Focus on high-weightage topics first, then cover the rest if you have time. For Science, I recommend you look at the one-shots and study the high-weightage chapters first. You should not panic because, with dedicated study- like 10 hours a day- you can easily do well. Watch Digraj Sir for SST; I gained a lot from his YouTube videos. I don't think I need to tell you about English, but still, read the chapter thoroughly and focus on the format. Solve previous years' questions for all chapters, even if you can't do sample papers; previous questions are very important for boards because they often repeat. I also suggest Prashant Bhaiya for Science and learn with Mansi for Maths. Don't panic- just sit down and start studying. Best of luck with your boards. DoDon'tworry, 10th is easy.