Generally seeing a blank screen when using the Test or Play options means one of two things:
1. Your story project doesn't have a Starting Point, in this case open your story project then select one of the Passages and used the Rocket Ship icon to mark it as the Starting Point.
2. Somehow the story project doesn't have a valid story format selected, in this case open your story project and select one of the story formats you don't want to use, then close and reopen the story project and select the story format you do want.
The above two issues can also effect a Story HTML file created using the Publish to File option, but if you are using the install-able release of the Twine 2 application then another cause of a blank screen is trying to open the application's Story Project HTML files instead of your Story HTML file. The Story Project HTML files are the ones found in the folder accessed via the Twine > Show Library menu items and these files are generally for the application's internal use only as is the folder itself, never save your Story HTML file within that folder.