ok ok, relax.
stop panicking; like literally, just stop panicking.
firstly, ask your teachers if you can have your papers back, or email them or contact them in anyway to ask them what topics you missed marks on the most.
then, once you have that information (worstly done topics), find questions online about those topics. idk if u've ever heard of google? it's a really cool browser that gives you access to things like past papers and sample questions.
print these out.
do the questions, without help, without your phone. just do them.
once you've done them, look up the mark scheme, red pen it, and work out your percentage on that set of questions.
do this for several more of the topics you struggled on.
now, prioritise the worstly done topic, and research videos on youtube on how to do them. if you still don't understand it,
don't! have! shame! to! ask! your! teacher!
re-do those exact same questions with the method you learnt from teachers or videos.
if necessary, use flashcards or any cards to write the formulae that you needed but didn't know how to use.
finally, the most important thing to do is relax and don't stress, have breaks but strict breaks because if you reward yourself with too many breaks then you'll literally go on your phone and lay in bed.
good luck!