I often get calls from parents and students panicking after a bad ACT test score. I tell them all the same thing; it's not time to worry yet! The good news is that when you really bomb a test, the fix to significantly increase your score is usually a lot simpler and easier than turning a pretty good score into a great score.
Step #1: Stop and Analyze
Before you panic looking at a low composite score, take the time to analyze what caused the poor performance. Ask yourself these questions:
Did you do poorly on all four subject tests or did just one or two drag down your overall score?
Did you have time to finish all the questions when you took the test or did you run out of time?
How were you feeling when you took the test? Sick, tired, full of anxiety?
Was this your first ACT test? Had you taken a practice test before this one?
Step #2: Figure Out a Game Plan
If you just did poorly across all four subject tests and you were full of anxiety or not feeling well physically, then the easy answer is that it may have just been a bad day. If you don't have a history of bombing tests, this is the most likely reason. Set aside 3 1/2 hours next Saturday morning and do a full practice test to verify that it just wasn't your day.
If you had trouble answering all the questions on time, then you need to hone your test taking skills in order to get through the test with time to spare. Any time you are feeling rushed, your score will suffer.
Step #3: Retake the ACT Test
Once you have figured out what happened and develop a strategy to address those issues, you will want to retake the test. Most students take it more than once, so don't feel bad.
If you need help putting a strategy together, get a good, inexpensive online course to help you.