Trying to reinstall Adobe Acrobat 9 Standard

I have the same problem as MJ5FBC above.  My computer went through an update and Adobe Reader was no longer available (I use it to open pdfs that are emailed to me, etc.) I also have Adobe Acrobat 9 Standard installed and I use that often to create pdfs and to extract pages, insert pages, etc. I've always had these 2 versions on my computer (updated as needed from Version 6 of Adobe Acrobat.  In any case, I reloaded Adobe Reader so that I could open emailed pdf files and it required me to uninstall other Acrobat products; therefore, I lost my Acrobat 9 Standard.  I just tried to reinstall Acrobat 9 from the disk I have and got the same message that MJ5FBC got: "Setup has detected that you already have a more functional product installed. Setup will now terminate".  So, in this process I have lost important functionality that I use frequently.  I don't understand how Adobe Acrobat DC has the same functionality without upgrading and paying for additional functionality.  I am very frustrated as I go into my busy accounting season and need the functionality that I had with both programs installed on my system.  Help!