如果你感到孤独、迷茫，请务必翻开这本书，它会给你勇气，助你挣脱生活的樊笼，寻到内心的光芒与自由。(which)

If you feel lonely and confused, be sure to open this book, which will give you the courage to break free from the cage of life and find the light and freedom in your heart.

考查状语从句和定语从句。引导条件状语从句，表示 “如果” 用if，主语为you，表示 “感到孤独、迷茫” 为feel lonely and confused，陈述事实用一般现在时；表示 “请务必” 为肯定祈使句，为be sure to；表示 “翻开这本书” 为open this book；后跟非限制性定语从句修饰先行词book，在从句作主语，指物，用which；表示 “给你做某事的勇气” 用give you the courage to do sth.；表示 “助你挣脱生活的樊笼” 可用to break free from the cage of life；表示 “寻到内心的光芒与自由” 为find the light and freedom in your heart。从句表示将来的动作用一般将来时。故翻译为：“If you feel lonely and confused, be sure to open this book, which will give you the courage to break free from the cage of life and find the light and freedom in your heart.”。