I cut the Pampas grass back in late February, and it hasn’t started growing back yet.

Question

I checked it out and it’s very dry. But the ground is moist. It was here when we bought the house.

Answer 1

Look down into the crown of the plant...do you see any green growth in there? Try to wiggle the plant at its base...is it firmly rooted, or does it wiggle quite a bit? If dead you can actually pull out roots. If this is an established grass; just give it more time. It just may be a slower spring.

https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/growing-pampas-grass.htm