My Japanese Lilac has wilted leaves. I recently had a patio put in as well as sod. I wonder if this has damaged its roots. This is the 3rd year since I planted it and it did not bloom this spring - which was before the landscaping.
Young plants often do not bloom reliably their first few year, so that in and of itself doesn't meant much. However, wilted leaves are a cause for concern. You don't say how far from the lilac the construction is, or if the sodding was done near it. Roots spread out quickly from the bush, and feeder roots are near the surface, so anything that covers the soil (concrete or sod) can interfere with the absorption of water, which leads to wilted leaves. Given some time and plenty of water, recovery should be swift. However, if the lilac was a distance from the distrubances, you might have some disease going on. Here's an article on Japanese lilac disease: http://hyg.ipm.illinois.edu/article.php?id=166
You might also want to take samples to the Extension Service to ask for analyis. This article will help you locate one: https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm