Go to Start>Control Panel>select Adobe Acrobat Reader DC>right-click>Change. Click the radio button "Repair installation ........" if it isn't already>click Next. Once the Repair is complete, reboot the machine and try launching Reader again.

Why is my Adobe Acrobat not opening?

The PDF file may be password-protected, damaged, or incompatible with Adobe Acrobat. Your installation of Adobe Acrobat may also be out of data or damaged, which may cause problems when you try to run it. ... Update, repair, and reinstall your version of Acrobat to enable it to function smoothly.

How do I fix Adobe Reader not opening?