You don't say how long you have had the cherry in that location.  These trees are fairly hardy.  Was it in an exposed location?  Overly dry or wet?  They do like regular watering - consdiering watering for a few weeks and add a flowering tree fertilizer spike. Rule of thumb is that if it bends not naps it is still alive.  It may come back.  If you have not had it long, it may not be in a good location (too much shade?, poor drainage? If it comes back you may need to consdier moving it.  Some general info about your cherry and problems you might have with it from Lee Wyatt:

• Soil requirements. A Kwanzan cherry tree can tolerate clay, loam, sandy, acidic, alkaline, occasionally wet, and well drained soils. That being said, this tree thrives in soil that is loose, and plenty of moisture. This tree is not one that is ideal for planting along an exposed street or a parking lot. Ideally speaking, the soil will have very good drainage, as well as plenty of humus, and has a low salt content.
• Sunlight. These cherry trees require a lot of sunlight. In fact, these trees should be planted in full sunlight and not in the shade. These trees do not deal well with excessive shade, and typically need at least six hours a day of full sunlight.
• Watering. On the average, a Kwanzan cherry tree is moderately drought resistant. However, if you want to see your tree really thrive, then provide a regular watering. Typically, means that you only need to water the tree deeply once a week. You can tell if you need to water your tree again, if the top three inches of soil around the tree are dry. Ideally, the Kwanzan cherry tree requires between 1/2 an inch to 1 inch of water each week.
• Nutrition. This tree doesn't really require a whole lot of attention throughout the year to ensure proper growth. Typically all you will need to do is mix in a slow releasing complete fertilizer, that has been designed for flowering trees, once a year to meet all of the tree's nutritional requirements.
• Climate. The Kwanzan cherry tree is not native to the United States, but does enjoy some decent life here. Originally, this cherry tree is from the Japanese islands, and from the Chinese mainland. That being said, the tree will thrive in the USDA hardiness zones of 5B through 9A. It can also put up with temperatures as low as 15 degrees below zero (Fahrenheit).
• Pruning. Pruning of this tree should be accomplished in the early summer, after the first blossoming has been experienced. This will allow you to identify the dead or diseased tree branches that need to be removed. Also remove any branches that appear to be crowded or growing back inwards towards the trunk.
• Common pest problems. The Kwanzan cherry tree is susceptible to aphids, mites and caterpillars