Presets are not applying to photos and not showing preview

Help! I just downloaded the most recent version of Lightroom Classis (not web based) on my computer and now the presets section is not working at all. When I hover over the preset it shows nothing on the image, when I click on it or double click on it it still does nothing. I have tried to import a preset I bought and this will not work or show the differnt variations in the pull down menu of the pack when I click on that preset pack. I have tried to uninstall and reinstall, I have rebooted my computer I have restored all presets to original and still nothing. I have no idea what is going on! and in the middle of the busiest season of the year..........