I recently planted a lilac bush. The leaves have become hard and stiff. We recently had high winds. Will the plant come back?

Answer 1

High winds can suck the moisture out of leaves leaving the plant stressed.
Make sure you maintain a consistent watering regimen to insure your plant the best success to get rooted into its new home.

https://www.gardeningknowhow.com/ornamental/shrubs/lilac/lilac-care-growing-and-planting-lilac-bush-plants.htm