Q.Planted a small blue spruce last summer, very hot here in summer. I had surgery and I know it wasn’t watered.
When I returned from surgery tree looked okay but dried out on one side. After a harsh winter the needles are dropping on one side and the branches are bare. I don’t think it is a bug, just from not being watered. The rest of tree looks great and is getting taller.
should I cut the bare branches off? Will the needles grow back? I lightly fertilized and put new mulch material around it and and watering it daily.

Certified GKH Gardening Expert
No, the dead branches and needles will not grow back.
You can prune the dead plant material from the tree.
https://www.gardeningknowhow.com/ornamental/trees/colorado-blue-spruce/care-for-colorado-spruce.htm