relearning knowledge i forgot!

probably so stupid to ask but im trying to revise now and realise i know nothing about the alevels im doing. like im going through my history textbooks and feel so overwhelmed because i remember nothing and i have exams so soon...

is there anyway to learn and consolidate and truly know the content quickly? i do ocr history, wotr, sa and russia. im struggling so much trying to relearn all the content for wotr and sa and i was wondering if anyone has any tips