Adobe Acrobat Reader - problem with opening pdf.

Hi, I have a problem with Adobe Acrobat Reader. My Adobe license has expired and I will not be purchasing another one. I wanted to download the free Acrobat Reader, but when I install it, it tells me that the program is already installed, but I can't find it anywhere on my computer and the pdf files still open in the classic paid Acrobat, so without a login and a valid license I can't read the pdf files. In my older computer I normally had both programs - the paid Acrobat and the free Acrobat Reader and it worked without any problems. Thanks so much for the advice!