Mitigating circumstances, in plain terms

Most institutions have a process — the name varies — for when something outside your control affected your work: illness, bereavement, a family emergency. It generally does not change a mark. What it typically gets you is an extension, a deferred sitting, or the attempt disregarded so it does not count against the number you are allowed.

It almost always needs evidence, and the claim itself carries its own deadline. Two things people get wrong: assuming it is reserved for extreme situations, and submitting after the result, by which point most processes will no longer look. Find out what it is called at your institution and what evidence it expects.