From Longman Dictionary of Contemporary Englishrack your brainsrack your brainsTHINK ABOUTto try very hard to remember or think of something I racked my brains, trying to remember his name. → rack
Examples from the Corpus
rack your brains• I've racked my brains, but at my age there are precious few left to rack.• Desperately, Irvin racked his brains, but there was nothing he could tell them.• There was a silence in the room as we all simultaneously racked our brains for a missing disease.• They sat in silence, racking their brains for the name of the road.• I waved back, racking my brains to remember who she was.• Which left Fabia racking her brains to think of how next best to get through to the woman.• She racked her brains, trying to remember what David had said.• Rachel racked her brains, trying to remember what Jamie had said of him - ruthless, living only for his ambition. 