Hi ,
It is good that you have uploaded your workbook , but in the absence of a detailed explanation of what you want done , there is very little that anyone can offer by way of help.
A pivot table summarizes data , and drilling down exposes the underlying data behind a summary figure.
In your workbook , which are these summary figures , and how would the result of a drill down be displayed ?
If you can present the layout of at least one such drill down , it may be easier for others to understand how your requirement can be fulfilled.
However , my personal opinion is that this is at best an academic exercise , since it will involve a lot of coding ; given that a pivot table does the same effortlessly , both on the part of the software and on the part of the user , I do not see why this exercise is being attempted.
Narayan