Hi, 

Can you provide photos for us. It is difficult to diagnose and provide appropriate guidance without seeing what the problem could be. You can send them in a response to this email. A few up close and some of the whole planting would be helpful. 

You can also review out Boxwood Diagnostic Page to go through symptoms and common problems to boxwood. Boxwood have a number of disease and insect issues, but they can be quite resilient with proper pruning. They are mostly slow growers though so if the pruning is too drastic it will take a few years before they start to fill out and rejuvenate. 

Emily

Hi, 

This looks like Volutella which is really common for Boxwood, especially when they get stressed. 

The site conditions in these photos appear to be sunny and hot with the surrounding pavement. Boxwood will be ok in those conditions with proper watering. Did you provide additional irrigation last summer during the drought or are you now in the heat wave and drought? Guide for watering trees and shrubs

You can prune out all the dead and dying branches on these and help mitigate stress symptoms and they should rebound, but as stated before they will take a a number of years to match the existing so you may want to replant. If you do, look for disease resistant varieties. They aren't maintenance free and still could have some issues but it will give you a better chance or not running into common problems. 

The link we provided in our first message has a boxwood pruning video that is helpful. It also will explain Volutella. 

Let us know if you have further questions, 

Emily

You're welcome