Individual tiles or roof shingles that have loosened due to high winds will endanger your property. Whether they've merely shifted a bit, leaving a gap, or they've completely gone off, they can allow water to infiltrate through your roof and into your roof space, causing damage.
If your entire roof structure has deteriorated, it may be because the roof timbers can no longer sustain the weight of the tiles, or because your home has an underlying structural issue. In that case, the entire roof may need to be rebuilt.
The lead flashing just at the end of your roof that seals the edges where chimneys and corners meet can fail and let water in if it has blown loose or been damaged.