Just do it. You might have not the work done for that class. You may be sorely under-prepared but don’t let that fear cripple you. If you go, you’ll be in a much better place. At the very least, you’ll have learned something. And the first step of getting back on track is admitting your mistakes.
So go to class. Wing it, if you have to. It’s much better than delaying the inevitable or thinking it will sort itself out. Just being there will have an effect on you. You’ll feel like a student and be motivated to work outside of class.
And don’t think your classmates are above you. Chances are some of them are just as under-prepared as you.
As long as you go, you’ll learn something. You’ll admit your mistake. And you will have made the first step to overcoming that and getting back on track.
Don’t make the mistake that too many students make. Don’t skip your classes.