What do you mean that the school can’t help? Late registration is allowed until March 12, though there is a late registration fee associated.
If the school isn’t offering the exam, or for some reason refuses to late register him, he will need to find a nearby school that is offering the test that will allow him to register through their school. With the current pandemic, this is proving to be difficult to home schooled student, who have to do the same.
There is/may be an alternative if you can’t find a school, but that’s TBD.
If your school doesn’t offer the exam you want to take, you’ll need to arrange to take the exam at a local school that does administer it.
Your first step is to search the AP Course Ledger. The AP Course Ledger is the official, up-to-date, comprehensive list of schools that have passed the AP Course Audit. You can search by country, state/province, or city to find a school where you might be able to test. After finding schools near you that offer the course or courses you want to take exams for, do an internet search for the school’s main phone number. Then call and ask to speak with the school’s AP coordinator to ask if the school is planning to allow homeschooled students to test there this year.
The deadline for exam ordering will be extended to March 12 for any students unable to find a school to order an AP Exam for them by November 13. In early 2021, we will share details about a contingency testing option for students unable to test in a school.