What does an attribute of A mean for a PDF. Can it be changed.

Search tools not working isn't a problem with file properties or Reader. It means there is nothing to find.

Two main reasons for this.

1. No text in the file. Just a scan. You may think you have text but if it's just a photo of text it can't search. Paid-for Acrobat can fo text recognition in this case.

2. Garbled text. A lot of diftesre puts it text that is junk text - when copied or searched it is garbage no matter what you see on screen. Almost impossible to fix.

Something is preventing normal Reader tools from working correctly. I tried changing file in question to read only and that did not solve the problem Don't see anything in security etc that would cause this problem. The document is almost 300 pages and very difficult to work with if the normal search tools won't work. I don't want to change or modify the document in any way. I have no ideas as to why search functions would not work.

As shown by Windows Properties, you mean? It is set by Windows when a file is created or modified, and usually cleared by a backup. No connection to searching, that's a red herring.