All of your teachers know, and they do not mind at all being ghosted by a shit student. If your parents are anywhere from normal to tiger mom, you're in for a shitload of trouble.

dust yourself off and make a plan to try again

There is only one way through school - You put in the effort and work and do the assignments yourself and take the tests without attempting to cheat. The purpose of the assignments are to prepare you to learn the class material. The purpose of the school is to prepare you for life after school. When you repeat the grade next year remember that how you begin your classes is even more important than what kind of effort you put in at the end. When you are behind on the subject you are learning, it is far harder to catch up than it would have been to stay current with the material as you go. A few children and young adults have genuine learning disabilities in certain subjects. In cases where this has been diagnosed, at least in schools in the USA, the school is obligated to help make a plan to address those deficiencies. When you first find you are struggling with understanding the subject then go to the teacher for advice and help. You will have to put in even more time and effort, but tutors or additional assignments can usually help you to learn. There are no shortcuts unless your family is wealthy enough to let their useless and lazy children coast through life on your parents money - But then you are obligated to spend the rest of your life dependent on your parents. Finally, tell your parents. The longer you put that off the worse the ultimate consequences. Show some character and deal with the situation.

Don't lie about this. Just don't. They're going to find out eventually. THEY WILL FIND OUT. And it'll be a hundred times better telling them than letting them find out on their own.

So, maybe im not the best person to give advice since I’ve never failed a class but being open and honest with your parents is the only way. Sure they’ll probably throw a fit and be disappointed, but it’s better they hear it from you. And we don’t know what the context is. If you’re failing despite trying really hard & studying, that’s a different story from being lazy and not caring. If you simply coasted and ignored assignments, skipped class etc. then YDI

Setbacks haopen my friend. We all fail and succeed in different ways, what matters is how we respond to it

Tell your parents ASAP. Bad news is NOT like fine wine, it does NOT get better with age. The longer you wait, the worse it'll look.