There can be several causes of a blank screen when a course launches and the solutions can depend on which course is being launched and the device or browser used.
We would suggest trying to following steps to resolve:
1. Check if Adobe Flash player is installed.
When Adobe Flash Player isn't installed, Flash based courses will only show a black screen when launched.
Instructions to enable this plugin for various browsers can be found here: https://atlasknowledge.freshdesk.com/support/solutions/folders/4000027533
2. Is the course window failing to open
If you click to launch the course and the window doesn't open, it is likely that your popup blocker is disabling access to to the course.
Instructions to disable your popup blocker can be found here: https://atlasknowledge.freshdesk.com/support/solutions/folders/4000027532