Can not open older PDF files

[jay fresno]

I'm using Windows 7 and Acrobat Pro DC. All updates are installed.

I'm able to open some PDF files. However, many, many older PDFs do not open. I get the following message:

I don't have the original files so cannot follow the instructions in the message.

[Bernd Alheit]

What can you see when you open the file in Notepad?

[jay fresno]

Thanks for responding. I see garbled text and symbols. Someone from Adobe contacted me, had me try a few things, and came to the conclusion that my files were hopelessly corrupt and nothing can be done about it. Unfortunately, I have a lot of these corrupt files.