The first 2 photos are under a bow window with some morning sun and some late afternoon sun. The second 2 photos are on the western facing side of the house with full sun from around 10:30am to 6:00pm. All of the plants are have been in those spots approximately 16 to 22 years. I'll send the 4th picture in a separate email. Thank you
Baltimore County Maryland
When stressed by poor site conditions, poor soils, environmental issues, etc. plants can be susceptible to disease and insect problems. Based on your photos it looks like the pachysandra was subject to volutella, a fungal disease and euonymus scale, a sucking insect. Pachysandra grows best in moist well drained soils in partial to full shade. It will be stressed in sun especially a western exposure.
See our website for photos and information on volutella http://extension.umd.edu/hgic/volutella-dieback-pachysandra-groundcover and euonymus scale. http://extension.umd.edu/hgic/armored-scales-groundcovers
At this point, it may be easiest to remove the pachysandra, clean up the bed, add some organic matter and start over with other plants or groundcovers.
Match the plants to the site sun versus shade and mature height and width. Groundcovers to consider for sun include sedums, plumbago, & creeping thyme.
Shade - ferns, heuchera, tiarella, phlox stolonifera. See more on our website http://extension.umd.edu/hgic/groundcover-list