Humor creates distance between you and the thing that was consuming your perspective.

Whatever has taken over your perspective has done so by being too close to see around. Humour puts a gap there. You are still in the situation and you are no longer entirely made of it, and that small separation is what allows thinking to resume.

If something has occupied you completely, look for the part of it that is genuinely ridiculous, because there almost always is one. Finding it does not trivialize the problem. It gives you somewhere to stand while you deal with it.