The Edit Text icon disappeared

I edit pdfs almost every day using Adobe Acrobat Standard DC. Today, I downloaded and opened a pdf to edit and found that the edit text icon had just disappeared. When I clicked on Tools, Edit, I got the message: This document restricts some AADC features to allow for extended features in AA Reader. To create a file that is not extended, choose File, Save a Copy. This doesn't resolve my problem, as I need to show my edits. I opened up older pdf files and I have the same problem. I restarted my computer as well. And, under Help, clicked Repair Installation.