Did you change the email address of your existing Apple ID or create a new Apple ID?
If you changed the email address, have you tried signing out of the App Store/iTunes, restarting the device, and then signing back in? If the purchases show in your ID Purchases History, contact iTunes Support for assistance. See the Apple Support articles below for contact information.
Purchase History Review.
iTunes Support – world wide
Apple Support schedule phone call
If necessary, try Twitter
https://twitter.com/AppleSupport. People have posted it may take an hour or more to get a response.
If you created a new Apple ID, you can try setting up Family Sharing between the IDs if you want to be able to share purchases made with the IDs.
Family Sharing.
Family Sharing - Set up.