Put your pen down, take five slow breaths, and move to a different question you can answer. Coming back to the tricky question later with a calmer head almost always helps. Examiners mark every question independently, so getting stuck on one does not affect your marks elsewhere. If you still cannot remember something, write down anything related to the topic, partial credit adds up. Practise this in your timed past papers so panic recovery becomes a trained response, not a first-time reaction in the exam hall.