Hello mcintoshj55.
Thank you for using Apple Support Communities. It's my understanding that you're unable to launch Keynote on your MacBook Air. You've done a great job trying to get this resolved so far! I'm happy to help.
By any chance are you using iCloud Drive with Keynote? If so, when you click to open Keynote check the lower left corner of the window that pops-up and see if you notice a 'New Document' button showing there. That would be the button you would want to click on if it is showing. You should also see a 'Cancel' button in the lower right. If you click on that then you can select 'File>New...' in the upper left of the window that loads and start a new document. The following article has some additional information:
Keynote for Mac: Use iCloud Drive with Keynote
If you are not using iCloud or you are not seeing the options listed above, I recommend testing the issue in safe mode. Starting in safe mode allows your Mac to run certain checks, remove caches, and prevent login items from automatically launching. This can isolate possible third party issues. Use the steps and information in the link below for assistance with safe mode:
Use safe mode to isolate issues with your Mac
If the issue persists, test in another user account. This will help determine if the issue is user specific or system wide.
How to test an issue in another user account on your Mac
Let us know the results. Please include specific error messages and any other troubleshooting steps you may have tried.
Have a great day!
