Thank you for posting on Adobe forums.
Please let me know where actually are your PDF files stored.
If the PDFs are stored online, then you can click on Document Cloud tab which will prompt you to sign in.
Once you are signed in, you could see all your files stored in your online account.
You might read discussion on the same issue on another forum thread:
[topic moved to Reader/Acrobat DC for Mobile forum]
Would you provide more information so that we can investigate the problem?
(1) What is the iOS version on your iPad?
(2) Is the Reader version installed on your iPad 15.0.5?
(3) Do you recall the version number of the previously installed Reader on your iPad? Was it 15.0.4 or older? (I am wondering if the last update skipped versions.)
(4) When you launched Acrobat Reader after the last update, did you see the screen like this?
Did you swipe from right to left several times and tap the blue Continue button to dismiss the screen?
(5) When you switch the file location to "Local", do you see any other PDF documents? Getting Started.pdf (sample PDF document) or no documents?
(6) After you sign into Adobe Document Cloud, do you see your PDF documents in "Recent"?
Thank you for your help.