This article provides a step-by-step guide on how to fix a roof leak in asphalt shingles. First, you must identify the source of the leak. Then, you should repair any damaged shingles and apply roofing cement to the area. After that, you should install a new shingle and apply a generous amount of roofing cement to the new shingle and surrounding area. Finally, you should seal the edges with roofing cement and apply a waterproof sealant. Following these steps will help ensure a long-lasting repair to your roof.