This is from a previous answer I gave:
"...to change the source data (where the pivot table pulls its
information from) you right click on any field in the pivot table, select
"Wizard...", and then click the "<Back" button.
- If the data is within the workbook you will see the sheet and the range will
be outlined.
- If the data comes from an outside source, like Access or a SQL db, then you
will click the button that says, "Get Data...", which will take you to the
[external] data source. You are on your own at that point on getting the
data."