Go to adobe.com, click the "Support" tab on the top of the screen, click on "Adobe Reader," and then select the "I can't open a PDF document" statement underneath "Troubleshooting." Paste the exact phrase you copied earlier into the search box on the right-hand side of the Adobe Support screen. Click "Enter."
Click on the "Adobe Troubleshooting" title that most closely matches the phrase you pasted into the search box. For example, if you paste "Cannot find or create the font..." into the Adobe Search box and select the one option available, you will receive specific directions detailing how to fix that particular problem. Follow the instructions you receive.