Many people look to repair keynote files when the file isn't opening and start giving error. The most commonly occurring situation is that the keynote file becomes invalid and the Mac system shows error message ( Unable to open "My Presentation" because it isn't a valid keynote file ). The reasons responsible for this can be sudden application crash when you were working on that file, virus infection etc. This may be quite frustrating for you, repair keynote file is the only option left for you if you don't want to waste your time in creating that file again. You can use the AutoRecovery option that comes inbuilt with the iWork suite that can recover the unsaved as well as repair keynote files. You can also try to use the Time Machine back up utility that saves a backup copy of a keynote file at regular interval after being set up. But if you are unable to repair it by any means then don't be worried as you can use iWork file recovery software. It can efficiently repair keynote file that will ready to edit and for the presentation.