Nobody wants a leaky roof. That’s the opposite of what a roof is supposed to do. You should have your roof inspected every year or two so that a roofer can spot small leaks and repair them before they become major issues. But if you or the house’s previous owner didn’t notice and repair smaller leaks, they could be visible leaks by now. Once leaks reach the point when they are visible, they are difficult to repair effectively. The better long-term solution is to replace the entire roof or at least the leaky section.
Missing or broken shingles are a sign of age or possible storm damage. Water damage, high winds, and hail can cause shingles to curl, tear, or fall off. Time is also a common culprit of this kind of roof damage. Exposure to the elements will eventually cause roofing materials to break down. Bald shingles are something else to watch out for. That means that the granules that protect the shingles have fallen off. You can replace problem areas in patches, but the wiser choice might be to replace the roof.