My holly bush has green berries
My oldest holly bush has thousands of green berries. And is dropping its leaves. Inner part all dead wood. What can I do?
Since you report this as your oldest bush, I'm guessing that you've never had a problem with berries forming before. Therefore the problem is probably not due to lack of pollination, light, or nutrients. There is a bug that can stop the berries from ripening: http://www.upenn.edu/paflora/plantclinic/hollyberrymidge.htm
That's the only report I can find; maybe someone else will have another experience.
Regarding the dropping leaves, look at the leaves especially before they drop, to see if there are spots or discolorations -- this is the way to identify possible diseases. This article will tell you more: https://www.gardeningknowhow.com/ornamental/shrubs/holly/diseases-of-holly-bushes-pests-and-diseases-damaging-holly-bushes.htm
Also, check the basic care, e.g. water, light, soil, minerals. https://www.gardeningknowhow.com/ornamental/shrubs/holly/growing-holly-bushes.htm
If these are okay, perhaps your plant needs a good pruning. Start by cutting out dead wood, then prune the living branches. This article will help you: https://www.gardeningknowhow.com/ornamental/shrubs/holly/trimming-holly-bushes-how-to-prune-holly-bushes.htm