I lost my presets when I uninstalled 12.0.1 and reinstalled 11.4

Help please! I uninstalled 12.0.1 Lightroom Classic because it seemed to be quite slow. I reinstalled 11.4 again. My presets are gone (which I assumed would happen) but when I try to import them, I get a message saying "Unable to import presets, all items were already imported." I tried importing them from my downloads, as well as my lightroom folder. I also unzipped them from the original download that I purchased. I tried in the preset import option in develop as well as in preferences presets while restarting lightroom. No luck. Any help would be appreciated. I have purchased at least 300.00 worth of presets from other photographers and I use them regularly for my work. Thank you! 

Jess