Here are a few possible reasons why QuickBooks won't open:
Sometimes, restarting your computer will resolve this issue. If not, then let's make sure to update your QuickBooks to the latest release. Please see Download from the Internet in this article: Update to the latest release of QuickBooks Desktop. Once done, try to open QuickBooks Desktop.
If you're getting the same result, here's an article for the other solutions: Resolve Problems Opening QuickBooks.
Feel free to leave a comment if there's anything else we can help you with QuickBooks. Thanks.