Database Pages missing when transferring from one site to another

Tried to move site from Coldstone non-responsive theme to Divi responsive theme. Individual customer data pages (1,400 total) didn’t transfer. Developer custom coded pages into the theme, added “Customers” to the dashboard. When search by zip, nothing shows as new site has no database.
I have the files developer used to build old site and the code. What is best way to solve problem?