want acrobat standard back - help

My acrobat standard was somehow replaced with the dc reader when I opened a pdf which has less functionality (no merging or extracting pages). I tried to reinstall acrobat standard but a pop up says the reader DC has more functionality and won't install. When I try to merge documents or edits I get a pop up that wants me to buy a subscription. I just want acrobat standard that I previously paid for. HELP!