You'll need to do way better as far as details if you want help.
Please start with version of InDesign and operating system as well what you're viewing the PDF with.
Sorry. First time user here.
I'm using InDesign 2015.2 (184.108.40.206), Mac OS X, and preview for viewing. I've tried to export my project to both print and interactive PDFs and have never had an issue before.
Preview is not a good application for PDFs.
Check it using Acrobat or Reader.
If it’s still blank, check preview mode in InDesign.