I live in Pacific Northwest and since last summer, I didn't take care for this guy:
Now it looks very bad shape. I guess lack of sun is part of the problem.
What can I do NOW?
How should I care for this one moving forward?
This appears to be a clear case of replacement. Erica/Calluna species like acid conditions and good drainage; being low growing and spreading sideways they are great for rock garden conditions, that is profiting from the soil between large rocks. The presence of the rock in the photo sort of confirms a kind of rock garden location.
Since they spread sideways and we are early spring, I would investigate the outside edges of the clump looking for likely new pieces with roots that could be used to start a new main planting. If you are lucky then buy a bag of soil suitable for acid loving plants and move the pieces to pots to get established while you rip out all traces of the old shrub. As you dig you may find more heavy rocks. Remove what roots you can and take the old soil out too which will have become exhausted by years of being left alone. Then replace the soil with acid suitable material and use the little pieces from the pots spread out in the empty space. If you cluster them in the middle then you will rapidly end up with the dead centre again. Dead centres are pretty much inevitable as the soil nutrients are consumed.
If you don't find any suitable pieces with roots then clip some of the flowers/leaves and take the sample to a local nursery that deals in Ericas and get them to match you up with a replacement.
This does look like one of the heaths or heathers - unfortunately, they need to be clipped over lightly after flowering once or twice a year (depending how often they flower), otherwise a bare, dead centre develops. I'm afraid this is what's happened with your shrub, and unfortunately, removing all the dead growth might mean you get no regrowth in those areas - they do not always regenerate from dead parts.
You can try cutting out all the dead wood and see if it regrows in a reasonable shape, otherwise, your only option is to remove it and replant the area. Some info in this link http://www.heathsandheathers.com/cart1/HHWebCart12010_Page1318.htm