Answer:
Firstly, don't stress, you'll get through it. Worrying will just slow you down, and learn Biology as something you get to do, and not a chore.
And if you want to relearn everything from the beginning, then I would recommend Crash Course's free Biology courses on YT, they also have Chemistry courses and everything. You can also go to Ask a Biologist, where you can do more than just ask questions.
There are so many more sources of information and everything, but one thing is; don't stress, that's the key.
Good luck, stay safe and healthy.
You'll get through it! Don't worry. If you want me to recommend more websites to you, just comment on this answer :D